cpp: don't exit with an error count, or we'll overflow to 0 and 'succeed'

@@ -1065,11 +1065,11 @@
 
         va_start(args, fmt);
         verror(fmt, args);
         va_end(args);
 
-        ++exfail;
+        exfail = 1;
 }
 
 /* VARARGS1 */
 void
 yyerror(char *fmt, ...)

@@ -1085,11 +1085,10 @@
 static void
 ppwarn(char *fmt, ...)
 {
         va_list args;
         int fail = exfail;
-        exfail = -1;
 
         va_start(args, fmt);
         verror(fmt, args);
         va_end(args);