Fix a crash by newline in text dialect

a simple "nl" in a text block could crash it, because it's a static
string, and not supposed to be free'd. "\n" is also supposed to be of
type wide_t*, or there'll be garbage text.

(gdb) bt
    #0  0x00007ffff72b2f73 in free () from /usr/lib/libc.so.6
    #1  0x00005555555fd956 in OS_Free (mem=0x5555556c49f8) at ../src/os/linux/host-lib.c:392
    #2  0x0000555555687413 in agg::rich_text::rt_reset (this=0x5555558f7d60) at ../src/agg/agg_truetype_text.cpp:135
    #3  0x0000555555652017 in agg::agg_graphics::agg_text (this=0x5555557ebde0, vectorial=1, p1=0x7fffffffc308, p2=0x7fffffffc310, block=0x7ffff61d6020) at ../src/agg/agg_graphics.cpp:1955
    #4  0x0000555555626103 in agg::rebdrw_text (gr=0x5555557ebde0, mode=1, p1=0x7fffffffc308, p2=0x7fffffffc310, block=0x7ffff61d6020) at ../src/os/host-draw-api-agg.cpp:413
    #5  0x0000555555623c01 in RXD_Draw (cmd=33, frm=0x7fffffffc3e0, ctx=0x7fffffffc5d0) at ../src/os/host-draw.c:571
    #6  0x000055555558b577 in Do_Commands (cmds=0x7ffff61d5fc0, context=0x7fffffffc5d0) at ../src/core/f-extension.c:585
    #7  0x000055555556b8a7 in RL_Do_Commands (blk=0x7ffff61d5fc0, flags=0, context=0x7fffffffc5d0) at ../src/core/a-lib.c:402
    #8  0x0000555555627b27 in agg::rebdrw_gob_draw (gob=0x555555940798, buf=0x7ffff5add000 '\377' <repeats 200 times>..., buf_size=..., abs_oft=..., clip_oft=..., clip_siz=...)
        at ../src/os/host-draw-api-agg.cpp:611
    #9  0x000055555562abf9 in process_gobs (ctx=0x5555559091f0, gob=0x555555940798) at ../src/os/linux/host-compositor.c:524
    #10 0x000055555562ae48 in process_gobs (ctx=0x5555559091f0, gob=0x555555940744) at ../src/os/linux/host-compositor.c:563
    #11 0x000055555562ae48 in process_gobs (ctx=0x5555559091f0, gob=0x5555559407ec) at ../src/os/linux/host-compositor.c:563
    #12 0x000055555562c037 in rebcmp_compose (ctx=0x5555559091f0, winGob=0x5555559407ec, gob=0x5555559407ec, only=0 '\000') at ../src/os/linux/host-compositor.c:691
    #13 0x000055555561affd in Draw_Window (wingob=0x5555559407ec, gob=0x5555559407ec) at ../src/os/host-view.c:225
    #14 0x000055555561b1a3 in Show_Gob (gob=0x5555559407ec) at ../src/os/host-view.c:288
    #15 0x000055555561b5ed in RXD_Graphics (cmd=5, frm=0x7fffffffd190, data=0x0) at ../src/os/host-view.c:338
    #16 0x000055555558b01a in Do_Command (value=0x7ffff6209110) at ../src/core/f-extension.c:456
    #17 0x0000555555570768 in Do_Next (block=0x7ffff61d5c00, index=9, op=0) at ../src/core/c-do.c:886
    #18 0x0000555555570e42 in Do_Blk (block=0x7ffff61d5c00, index=7) at ../src/core/c-do.c:1017
    #19 0x00005555555790f4 in Do_Function (func=0x7ffff6209070) at ../src/core/c-function.c:415
    #20 0x0000555555570768 in Do_Next (block=0x7ffff61d9a60, index=3, op=0) at ../src/core/c-do.c:886
    #21 0x0000555555570587 in Do_Next (block=0x7ffff61d9a60, index=0, op=0) at ../src/core/c-do.c:860
    #22 0x0000555555570e42 in Do_Blk (block=0x7ffff61d9a60, index=0) at ../src/core/c-do.c:1017
    #23 0x00005555555a1bc3 in N_while (ds=0x7ffff6209010) at ../src/core/n-loop.c:690
    #24 0x0000555555578bdd in Do_Native (func=0x7ffff6208fb0) at ../src/core/c-function.c:289
    #25 0x0000555555570768 in Do_Next (block=0x7ffff61d9aa0, index=5, op=0) at ../src/core/c-do.c:886
    #26 0x0000555555570e42 in Do_Blk (block=0x7ffff61d9aa0, index=2) at ../src/core/c-do.c:1017
    #27 0x00005555555790f4 in Do_Function (func=0x7ffff6208ed0) at ../src/core/c-function.c:415
    #28 0x0000555555572734 in Apply_Function (wblk=0x7ffff61d9aa0, widx=0, func=0x7ffff6208ed0, args=0x7fffffffd530) at ../src/core/c-do.c:1528
    #29 0x0000555555572883 in Apply_Func (where=0x7ffff61d9aa0, func=0x555555844da0) at ../src/core/c-do.c:1555
    #30 0x000055555559e5d2 in N_wake_up (ds=0x7ffff6208db0) at ../src/core/n-io.c:415
    #31 0x0000555555578bdd in Do_Native (func=0x7ffff6208e10) at ../src/core/c-function.c:289
    #32 0x0000555555570768 in Do_Next (block=0x7ffff7fbf1e0, index=6, op=0) at ../src/core/c-do.c:886
    #33 0x000055555556fbe8 in Do_Args (func_offset=105, path=0x0, block=0x7ffff7fbf1e0, index=3) at ../src/core/c-do.c:668
    #34 0x00005555555706ba in Do_Next (block=0x7ffff7fbf1e0, index=2, op=0) at ../src/core/c-do.c:879
    #35 0x0000555555570e42 in Do_Blk (block=0x7ffff7fbf1e0, index=2) at ../src/core/c-do.c:1017
    #36 0x000055555559b221 in N_either (ds=0x7ffff6208bd0) at ../src/core/n-control.c:596
    #37 0x0000555555578bdd in Do_Native (func=0x7ffff6208c30) at ../src/core/c-function.c:289
    #38 0x0000555555570768 in Do_Next (block=0x7ffff7fbf220, index=15, op=0) at ../src/core/c-do.c:886
    #39 0x0000555555570e42 in Do_Blk (block=0x7ffff7fbf220, index=10) at ../src/core/c-do.c:1017
    #40 0x00005555555a1bc3 in N_while (ds=0x7ffff6208bd0) at ../src/core/n-loop.c:690
    #41 0x0000555555578bdd in Do_Native (func=0x7ffff6208b70) at ../src/core/c-function.c:289
    #42 0x0000555555570768 in Do_Next (block=0x7ffff7fbf2e0, index=12, op=0) at ../src/core/c-do.c:886
    #43 0x0000555555570e42 in Do_Blk (block=0x7ffff7fbf2e0, index=9) at ../src/core/c-do.c:1017
    #44 0x00005555555790f4 in Do_Function (func=0x7ffff62089d0) at ../src/core/c-function.c:415
    #45 0x0000555555572734 in Apply_Function (wblk=0x7ffff7fbf2e0, widx=0, func=0x7ffff62089d0, args=0x7fffffffda30) at ../src/core/c-do.c:1528
    #46 0x0000555555572883 in Apply_Func (where=0x7ffff7fbf2e0, func=0x555555844140) at ../src/core/c-do.c:1555
    #47 0x000055555557979c in Awake_System (ports=0x7ffff61d5640, only=0) at ../src/core/c-port.c:183
    #48 0x0000555555579890 in Wait_Ports (ports=0x7ffff61d5640, timeout=4294967295, only=0) at ../src/core/c-port.c:217
    #49 0x000055555559e463 in N_wait (ds=0x7ffff6208890) at ../src/core/n-io.c:374
    #50 0x0000555555578bdd in Do_Native (func=0x7ffff62088f0) at ../src/core/c-function.c:289
    #51 0x0000555555570768 in Do_Next (block=0x7ffff61d9800, index=2, op=0) at ../src/core/c-do.c:886
    #52 0x0000555555570e42 in Do_Blk (block=0x7ffff61d9800, index=0) at ../src/core/c-do.c:1017
    rebol#53 0x00005555555790f4 in Do_Function (func=0x7ffff6208870) at ../src/core/c-function.c:415
    rebol#54 0x0000555555570768 in Do_Next (block=0x7ffff61d92e0, index=1, op=0) at ../src/core/c-do.c:886
    rebol#55 0x0000555555570e42 in Do_Blk (block=0x7ffff61d92e0, index=0) at ../src/core/c-do.c:1017
    rebol#56 0x000055555559b300 in N_if (ds=0x7ffff6208730) at ../src/core/n-control.c:623
    rebol#57 0x0000555555578bdd in Do_Native (func=0x7ffff6208790) at ../src/core/c-function.c:289
    rebol#58 0x0000555555570768 in Do_Next (block=0x7ffff61d9300, index=50, op=0) at ../src/core/c-do.c:886
    rebol#59 0x0000555555570e42 in Do_Blk (block=0x7ffff61d9300, index=46) at ../src/core/c-do.c:1017
    rebol#60 0x00005555555790f4 in Do_Function (func=0x7ffff62085f0) at ../src/core/c-function.c:415
    rebol#61 0x0000555555570768 in Do_Next (block=0x7ffff61d60e0, index=28, op=0) at ../src/core/c-do.c:886
    rebol#62 0x0000555555570e42 in Do_Blk (block=0x7ffff61d60e0, index=26) at ../src/core/c-do.c:1017
    rebol#63 0x000055555559b02d in N_do (ds=0x7ffff6208470) at ../src/core/n-control.c:522
    rebol#64 0x0000555555578bdd in Do_Native (func=0x7ffff62084d0) at ../src/core/c-function.c:289
    rebol#65 0x0000555555570768 in Do_Next (block=0x7ffff7fc5140, index=6, op=0) at ../src/core/c-do.c:886
    rebol#66 0x0000555555570e42 in Do_Blk (block=0x7ffff7fc5140, index=3) at ../src/core/c-do.c:1017
    rebol#67 0x000055555559b221 in N_either (ds=0x7ffff6208370) at ../src/core/n-control.c:596
    rebol#68 0x0000555555578bdd in Do_Native (func=0x7ffff62083d0) at ../src/core/c-function.c:289
    rebol#69 0x0000555555570768 in Do_Next (block=0x7ffff7fc51c0, index=20, op=0) at ../src/core/c-do.c:886
    rebol#70 0x0000555555570e42 in Do_Blk (block=0x7ffff7fc51c0, index=11) at ../src/core/c-do.c:1017
    rebol#71 0x000055555559b221 in N_either (ds=0x7ffff6208270) at ../src/core/n-control.c:596
    rebol#72 0x0000555555578bdd in Do_Native (func=0x7ffff62082d0) at ../src/core/c-function.c:289
    rebol#73 0x0000555555570768 in Do_Next (block=0x7ffff7fc5200, index=11, op=0) at ../src/core/c-do.c:886
    rebol#74 0x0000555555570e42 in Do_Blk (block=0x7ffff7fc5200, index=5) at ../src/core/c-do.c:1017
    rebol#75 0x000055555559b221 in N_either (ds=0x7ffff6208170) at ../src/core/n-control.c:596
    rebol#76 0x0000555555578bdd in Do_Native (func=0x7ffff62081d0) at ../src/core/c-function.c:289
    rebol#77 0x0000555555570768 in Do_Next (block=0x7ffff7fc5240, index=76, op=0) at ../src/core/c-do.c:886
    rebol#78 0x0000555555570e42 in Do_Blk (block=0x7ffff7fc5240, index=71) at ../src/core/c-do.c:1017
    rebol#79 0x00005555555790f4 in Do_Function (func=0x7ffff6208090) at ../src/core/c-function.c:415
    rebol#80 0x0000555555572734 in Apply_Function (wblk=0x7ffff7fc5240, widx=0, func=0x7ffff6208090, args=0x7fffffffe350) at ../src/core/c-do.c:1528
    rebol#81 0x0000555555572a40 in Do_Sys_Func (inum=34) at ../src/core/c-do.c:1588
    rebol#82 0x0000555555573f89 in Init_Mezz (reserved=0) at ../src/core/c-do.c:2320
    rebol#83 0x000055555556b558 in RL_Start (
        bin=0x5555556b63a0 <Reb_Init_Code> "x\234\325=is\334\066\226\373\231\277\002\241kK\322x\350>t\330鉣rdg\354\335\\e{j>t\261RT\223\222\070\352&{H\266e\215\343\377\276\357\302ţ[\262\235\311l\245b\221 \360\360\360\200w\342\001\375\027uV\256o\253\374\362\252Q\257_|\367\363\017\352m\266\270*\312ey\231g\265:\216~*\337E\323\361\344\311hr8;\236\314\306_Gdz\361\070\310W\353\262jԪL7\313L̓&o\226\331L\205\f\343P\275\375\341ͻɣ\261ZWeS.ʥ\252\027W\331*\v\203wYU\347e1S\343G'\217&A\221\254\240Y\263\254\203\030\240\244\331\371\346r\026\024e\221", <incomplete sequence \331>..., len=9009, script=0x0, script_len=0, flags=0)
        at ../src/core/a-lib.c:193
    rebol#84 0x00005555555fb344 in main (argc=2, argv=0x7fffffffe708) at ../src/os/host-main.c:235
    (gdb) frame 2
    #2  0x0000555555687413 in agg::rich_text::rt_reset (this=0x5555558f7d60) at ../src/agg/agg_truetype_text.cpp:135
    135					OS_Free(attr.text);
    (gdb) p attr
    $1 = {index = 10, name = 0x5555557a8af0 "/usr/share/fonts/TTF/arial.ttf", name_free = false, bold = 0, italic = 0, underline = 1, size = 18, color = {r = 128 '\200', g = 128 '\200', b = 128 '\200',
        a = 255 '\377'}, offset_x = 2, offset_y = 2, space_x = 0, space_y = 0, shadow_x = 0, shadow_y = 0, shadow_color = {r = 0 '\000', g = 0 '\000', b = 0 '\000', a = 255 '\377'}, shadow_blur = 0,
      text = 0x5555556c49f8 L"\n\x4f000000\xcf000000", text_free = true, isPara = true, para = {origin_x = 2, origin_y = 2, margin_x = 2, margin_y = 2, indent_x = 0, indent_y = 0, tabs = 40, wrap = 1,
        scroll_x = 0, scroll_y = 0, align = 19, valign = 23}, asc = 14, desc = 2, char_height = 13}
    (gdb) quit

src/os/host-text-api-agg.cpp

@@ -192,7 +192,7 @@ namespace agg
 
 	extern "C" void rt_newline(void* rt, REBINT index)
 	{
-		((rich_text*)rt)->rt_set_text((REBCHR*)"\n", TRUE);
+		((rich_text*)rt)->rt_set_text((REBCHR*)L"\n", FALSE);
 		((rich_text*)rt)->rt_push(index);
 	}