[totem] main: Fix crasher on startup

[Bastien Nocera <hadess src gnome org>]

commit 7350fc9ff39d3f2e5f7ed90fcd0d20fa86829faa
Author: Bastien Nocera <hadess hadess net>
Date:   Fri Feb 28 16:54:09 2014 +0100

    main: Fix crasher on startup
    
    Not all sources have tags

 src/totem-grilo.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/totem-grilo.c b/src/totem-grilo.c
index 0f8cb4f..cff626d 100644
--- a/src/totem-grilo.c
+++ b/src/totem-grilo.c
@@ -255,6 +255,8 @@ source_is_adult (GrlSource *source)
        const char **tags;
 
        tags = grl_source_get_tags (source);
+       if (!tags)
+               return FALSE;
 
        return strv_has_prefix (tags, "adult");
 }