Fix file cache serialization

Author: DanielEScherzer

ext/opcache/zend_file_cache.c

@@ -431,6 +431,10 @@ static void zend_file_cache_serialize_zval(zval                     *zv,
 			/* Used by static properties. */
 			SERIALIZE_PTR(Z_INDIRECT_P(zv));
 			break;
+		case IS_PTR:
+			/* Used by attributes on constants */
+			SERIALIZE_PTR(Z_PTR_P(zv));
+			break;
 		default:
 			ZEND_ASSERT(Z_TYPE_P(zv) < IS_STRING);
 			break;