Replaced plain 0's and 1's in exit statements with EXIT_SUCCESS or EXIT_FAILURE

test/ref/hanoi.c

@@ -62,7 +62,7 @@ int main(int argc,char **argv)
         #ifdef USECMDLINE
         if (argc < 2) {
                 printf("Usage: %s [duration] [disks]\n", argv[0]);
-                exit(1);
+                exit(EXIT_FAILURE);
         }
         else
         {

test/ref/wf1.c

@@ -45,7 +45,7 @@ err(s) char *s; {
 int err(char *s) {
 #endif
         printf("? %s\n", s);
-        exit(1);
+        exit(EXIT_FAILURE);
 }
 
 /* getword - get next input word into buf, return 0 on EOF */