Fix #79177 Check for undefined result in zend_ffi_callback_trampoline.

This situation can happen when userland exception is thrown within callback body.

Author: lisachenko

ext/ffi/ffi.c

@@ -878,7 +878,7 @@ static void zend_ffi_callback_trampoline(ffi_cif* cif, void* ret, void** args, v
 	free_alloca(fci.params, use_heap);
 
 	ret_type = ZEND_FFI_TYPE(callback_data->type->func.ret_type);
-	if (ret_type->kind != ZEND_FFI_TYPE_VOID) {
+	if (ret_type->kind != ZEND_FFI_TYPE_VOID && Z_TYPE(retval) != IS_UNDEF) {
 		zend_ffi_zval_to_cdata(ret, ret_type, &retval);
 	}
 }