Fix C23 syntax for VS16 (CI runs VS22)

Author: KalleZ

ext/pdo/pdo_stmt.c

@@ -640,7 +640,7 @@ static bool pdo_call_fetch_object_constructor(zend_function *constructor, HashTa
 	zval retval_constructor_call;
 	zend_fcall_info fci = {
 		.size = sizeof(zend_fcall_info),
-		.function_name = {},
+		.function_name = { 0 },
 		.object = Z_OBJ_P(return_value),
 		.retval = &retval_constructor_call,
 		.param_count = 0,

ext/spl/spl_iterators.c

@@ -3086,7 +3086,7 @@ PHP_FUNCTION(iterator_apply)
 	spl_iterator_apply_info apply_info = {
 		.count = 0,
 		.params_ht = NULL,
-		.fcc = {},
+		.fcc = { 0 },
 	};
 
 	/* The HashTable is used to determine positional arguments */