[gnome-software] trivial: Fix a possible crash spotted by clang

[Richard Hughes <rhughes src gnome org>]

commit 13bf5788258c9a6fc49961ef1428ea728fb16078
Author: Richard Hughes <richard hughsie com>
Date:   Fri Apr 22 18:25:34 2016 +0100

    trivial: Fix a possible crash spotted by clang

 src/gs-shell-details.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/gs-shell-details.c b/src/gs-shell-details.c
index 2064ede..6969862 100644
--- a/src/gs-shell-details.c
+++ b/src/gs-shell-details.c
@@ -1080,7 +1080,7 @@ gs_shell_details_review_button_clicked_cb (GsReviewRow *row,
 static void
 gs_shell_details_refresh_reviews (GsShellDetails *self)
 {
-       GArray *review_ratings;
+       GArray *review_ratings = NULL;
        GPtrArray *reviews;
        gboolean show_review_button = TRUE;
        gboolean show_reviews = FALSE;