Fix memory leak of function attribute hash table

Found while implementing php#7921.

Author: TimWolla

Zend/zend_opcode.c

@@ -153,6 +153,12 @@ ZEND_API void zend_function_dtor(zval *zv)
 		ZEND_ASSERT(function->common.function_name);
 		zend_string_release_ex(function->common.function_name, 1);
 
+		if (function->common.attributes) {
+			zend_hash_destroy(function->common.attributes);
+			free(function->common.attributes);
+			function->common.attributes = NULL;
+		}
+
 		/* For methods this will be called explicitly. */
 		if (!function->common.scope) {
 			zend_free_internal_arg_info(&function->internal_function);