[gnome-software/gnome-3-20] trivial: Fix FALSE/NULL confusion spotted with GCC6

[Richard Hughes <rhughes src gnome org>]

commit 06ad25aa077106e2f4a2b92ed827e4b943e174a7
Author: Richard Hughes <richard hughsie com>
Date:   Thu Mar 3 10:47:20 2016 +0000

    trivial: Fix FALSE/NULL confusion spotted with GCC6

 src/gs-app.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/gs-app.c b/src/gs-app.c
index 9cddc7c..c300875 100644
--- a/src/gs-app.c
+++ b/src/gs-app.c
@@ -1641,7 +1641,7 @@ gs_app_set_rating (GsApp *app, gint rating)
 GArray *
 gs_app_get_review_ratings (GsApp *app)
 {
-       g_return_val_if_fail (GS_IS_APP (app), FALSE);
+       g_return_val_if_fail (GS_IS_APP (app), NULL);
        return app->review_ratings;
 }