more graphics option parsing

     The recent fix for OPTIONS=noDECgraphics,IBMgraphics would have been
subject to lint complaints for some configurations.  Declare the extra
variable with the same conditional tests which control its use; somewhat
messier, but lint free.

     My previous fix only solves this problem for the initial config file
parsing.  If you enable IBMgraphics (by any method), then interactively
use the 'O' command to try to enable DECgrahpics and to _simultaneously_
disable IBMgraphics instead of letting it be overridden, you will end up
with IBMgraphics on and DECgraphics off.  That's because the menu entries
are processed in order, and after it has acted upon the request to set
DECgraphics on, the IBMgraphics flag will have been switched off; then
when it acts upon the request to toggle IBMgraphics, that flag will end
up being switched back on (switching DECgraphics back off in the process).

     This erroneous behavior was the same prior to last week's patch;
I just hadn't noticed yet.  It looks like we really do need to change
{ASCII,DEC,IBM,MAC}graphics into a single compound option.

src/options.c

@@ -2309,9 +2309,16 @@ boolean tinitial, tfrom_file;
 	 * options list
 	 */
 	for (i = 0; boolopt[i].name; i++) {
-		boolean was_set;
-
 		if (match_optname(opts, boolopt[i].name, 3, FALSE)) {
+#if defined(TERMLIB) || defined(ASCIIGRAPH) || defined(MAC_GRAPHICS_ENV)
+			/* need to remember previous XXXgraphics setting
+			   in order to prevent explicit "noXXXgraphics" from
+			   overriding a preceding "YYYgraphics" request;
+			   noXXXgraphics will reset to ordinary ASCII only
+			   if/when XXXgraphics is currently in effect */
+			boolean old_gfx = boolopt[i].addr && *boolopt[i].addr;
+#endif
+
 			/* options that don't exist */
 			if (!boolopt[i].addr) {
 			    if (!initial && !negated)
@@ -2325,7 +2332,6 @@ boolean tinitial, tfrom_file;
 			    return;
 			}
 
-			was_set = *(boolopt[i].addr);
 			*(boolopt[i].addr) = !negated;
 
 			/* 0 means boolean opts */
@@ -2351,21 +2357,21 @@ boolean tinitial, tfrom_file;
 			    need_redraw = TRUE;
 # ifdef TERMLIB
 			    if ((boolopt[i].addr) == &iflags.DECgraphics) {
-				if (iflags.DECgraphics != was_set)
+				if (iflags.DECgraphics != old_gfx)
 				    switch_graphics(iflags.DECgraphics ?
 						DEC_GRAPHICS : ASCII_GRAPHICS);
 			    }
 # endif
 # ifdef ASCIIGRAPH
 			    if ((boolopt[i].addr) == &iflags.IBMgraphics) {
-				if (iflags.IBMgraphics != was_set)
+				if (iflags.IBMgraphics != old_gfx)
 				    switch_graphics(!negated ?
 						IBM_GRAPHICS : ASCII_GRAPHICS);
 			    }
 # endif
 # ifdef MAC_GRAPHICS_ENV
 			    if ((boolopt[i].addr) == &iflags.MACgraphics) {
-				if (iflags.MACgraphics != was_set)
+				if (iflags.MACgraphics != old_gfx)
 				    switch_graphics(iflags.MACgraphics ?
 						MAC_GRAPHICS : ASCII_GRAPHICS);
 			    }