remove Csetjmp__Jumpbuf_size from Modula-3 interface, will replace wi…

…th private C/m3front-only

m3_jmpbuf_size

m3-libs/m3core/src/C/Common/Csetjmp.i3

@@ -5,11 +5,23 @@
 UNSAFE INTERFACE Csetjmp;
 FROM Ctypes IMPORT int;
 
-(* jmp_buf is allocated with alloca(Csetjmp__Jumpbuf_size)
+(* TODO? Move this to C?
+
    "u" in "ulongjmp" is probably for "underscore".
    This variant of longjmp never restores the signal mask.
+   Because we believe we never change it?
+   And restoring it is less efficient? (Requires possible kernel
+   interaction?)
+
+   If the platform only has "regular" longjmp and no signal mask,
+   e.g. Win32, then this is resolved to that.
+
+   This function does not return in the usual sense.
+   This is used to raise an exception.
+   This is subject to be removed, either by using C, or "libunwind", or
+   Win32 exceptions, or C++ exceptions.
+
 *)
-<*EXTERNAL "Csetjmp__Jumpbuf_size" *> VAR Jumpbuf_size: INTEGER;
 <*EXTERNAL "Csetjmp__ulongjmp" *> PROCEDURE ulongjmp (env: ADDRESS; val: int);
 
 END Csetjmp.