Use APPLY_STOP in pcre_clean_cache()

Once num_clean has reached 0, we never remove any more elements anyway.

Author: iluuu1994

ext/pcre/php_pcre.c

@@ -525,7 +525,7 @@ static int pcre_clean_cache(zval *data, void *arg)
 		(*num_clean)--;
 		return ZEND_HASH_APPLY_REMOVE;
 	} else {
-		return ZEND_HASH_APPLY_KEEP;
+		return ZEND_HASH_APPLY_STOP;
 	}
 }
 /* }}} */