support 32-bit runes by using Runemax not 0xffff.

Reference: /n/sources/patch/saved/bloated-rune-unicode
Date: Fri Jan 29 07:35:01 CET 2010
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/unicode.c	Fri Jan 29 07:34:44 2010
+++ /sys/src/cmd/unicode.c	Fri Jan 29 07:34:42 2010
@@ -51,13 +51,13 @@
 			return "bad range";
 		}
 		min = strtoul(q, &q, 16);
-		if(min<0 || min>0xFFFF || *q!='-')
+		if(min<0 || min>Runemax || *q!='-')
 			goto err;
 		q++;
 		if(strchr(hex, *q) == 0)
 			goto err;
 		max = strtoul(q, &q, 16);
-		if(max<0 || max>0xFFFF || max<min || *q!=0)
+		if(max<0 || max>Runemax || max<min || *q!=0)
 			goto err;
 		i = 0;
 		do{
@@ -111,7 +111,7 @@
 			return "bad char";
 		}
 		m = strtoul(q, &q, 16);
-		if(m<0 || m>0xFFFF || *q!=0)
+		if(m<0 || m>Runemax || *q!=0)
 			goto err;
 		Bprint(&bout, "%C", m);
 		if(!text)