a couple of silly bugs that caused compilation to fail.

Notes:
Sun Jul 24 23:08:56 EDT 2005 rsc
    There is no way this patch is right.  
    
    	while(++s != NULL)
    
    is only ever going to be false when s==(void*)~0. 
    Good luck with that.
    


Reference: /n/sources/patch/sorry/subr-compile
Date: Sat Jul 23 20:50:38 CES 2005
Reviewed-by: rsc

--- /sys/src/cmd/plot/libplot/subr.c	Sat Jul 23 20:50:16 2005
+++ /sys/src/cmd/plot/libplot/subr.c	Sat Jul 23 20:50:14 2005
@@ -13,7 +13,7 @@
 struct penvir *e0 = E, *e1 = &E[1], *esave;
 bcolor(char *s){
 	int c;
-	while (*s != 0) {
+	while (s != NULL) {
 		switch (*s) {
 		case '0': case '1': case '2': case '3': case '4':
 		case '5': case '6': case '7': case '8': case '9':
@@ -48,7 +48,7 @@
 			e1->pslant = (180. - atof(s + 1)) / RADIAN; 
 			return(-1);
 		}
-		while (*++s != 0) 
+		while (++s != NULL) 
 			if (*s == '/') {
 				s++;
 				break;