Reset required_num_args for disabled functions

Otherwise we may get arginfo/zpp mismatch errors.

Author: nikic

Zend/tests/bug69315.phpt

@@ -12,6 +12,9 @@ var_dump(defined("PHP_VERSION"));
 var_dump(constant("PHP_VERSION"));
 var_dump(call_user_func("strlen"));
 var_dump(is_string("xxx"));
+var_dump(is_string());
+
+?>
 --EXPECTF--
 bool(false)
 bool(true)
@@ -30,3 +33,6 @@ NULL
 
 Warning: is_string() has been disabled for security reasons in %sbug69315.php on line %d
 NULL
+
+Warning: is_string() has been disabled for security reasons in %s on line %d
+NULL

Zend/zend_API.c

@@ -2650,6 +2650,7 @@ ZEND_API int zend_disable_function(char *function_name, size_t function_name_len
 		zend_free_internal_arg_info(func);
 	    func->fn_flags &= ~(ZEND_ACC_VARIADIC | ZEND_ACC_HAS_TYPE_HINTS | ZEND_ACC_HAS_RETURN_TYPE);
 		func->num_args = 0;
+		func->required_num_args = 0;
 		func->arg_info = NULL;
 		func->handler = ZEND_FN(display_disabled_function);
 		return SUCCESS;