[gtksourceview] FileLoader: add missing g_returns

[Sébastien Wilmet <swilmet src gnome org>]

commit 1511dae2e5be643eaddb78ec8b8c415aac3ff42c
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sat Apr 30 18:19:32 2016 +0200

    FileLoader: add missing g_returns

 gtksourceview/gtksourcefileloader.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtksourceview/gtksourcefileloader.c b/gtksourceview/gtksourcefileloader.c
index e4c3278..dcf560f 100644
--- a/gtksourceview/gtksourcefileloader.c
+++ b/gtksourceview/gtksourcefileloader.c
@@ -918,6 +918,9 @@ gtk_source_file_loader_set_candidate_encodings (GtkSourceFileLoader *loader,
 {
        GSList *list;
 
+       g_return_if_fail (GTK_SOURCE_IS_FILE_LOADER (loader));
+       g_return_if_fail (loader->priv->task == NULL);
+
        list = g_slist_copy (candidate_encodings);
        list = _gtk_source_encoding_remove_duplicates (list, GTK_SOURCE_ENCODING_DUPLICATES_KEEP_FIRST);