make agnostic

Reference: /n/sources/patch/applied/rune6-libdraw
Date: Thu Apr 25 01:00:07 CES 2013
Signed-off-by: geoff@plan9.bell-labs.com

--- /sys/src/libdraw/buildfont.c	Thu Apr 25 01:00:03 2013
+++ /sys/src/libdraw/buildfont.c	Thu Apr 25 01:00:03 2013
@@ -70,7 +70,7 @@
 		}
 		max = strtol(s, &s, 0);
 		s = skip(s);
-		if(*s==0 || min>=65536 || max>=65536 || min>max){
+		if(*s==0 || min>=Runemax || max>=Runemax || min>max){
 			werrstr("illegal subfont range");
     Err3:
 			freefont(fnt);