[grilo-plugins] youtube: Add missing sentinel for g_strconcat()

[Colin Walters <walters src gnome org>]

commit b013d98e8915900053adda06aadf9dd0d9129c02
Author: Colin Walters <walters verbum org>
Date:   Sun Jun 14 11:04:24 2015 -0400

    youtube: Add missing sentinel for g_strconcat()
    
    The build was failing in Continuous.

 src/youtube/grl-youtube.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/youtube/grl-youtube.c b/src/youtube/grl-youtube.c
index 7f06f89..44548d2 100644
--- a/src/youtube/grl-youtube.c
+++ b/src/youtube/grl-youtube.c
@@ -616,7 +616,7 @@ build_categories_directory_read_cb (GObject *source_object,
 
     cat_info = g_slice_new (CategoryInfo);
     cat_info->id = g_strconcat (YOUTUBE_CATEGORIES_ID, "/",
-                                gdata_category_get_term (category));
+                                gdata_category_get_term (category), NULL);
     cat_info->name = g_strdup (gdata_category_get_label (category));
     all = g_list_prepend (all, cat_info);
     total++;