[grilo] Fix compilation warning

[Marc-Andre Lureau <malureau src gnome org>]

commit 5b865c87998a40ea3305af00eaa26fa458ac7ec3
Author: Marc-André Lureau <marcandre lureau gmail com>
Date:   Fri Nov 14 12:45:03 2014 +0100

    Fix compilation warning
    
    data/grl-related-keys.c: In function 'grl_related_keys_get_boolean':
    data/grl-related-keys.c:474:419: warning: return makes integer from
    pointer without a cast [enabled by default]
       g_return_val_if_fail (GRL_IS_RELATED_KEYS (relkeys), NULL);
    
    https://bugzilla.gnome.org/show_bug.cgi?id=740113

 src/data/grl-related-keys.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/data/grl-related-keys.c b/src/data/grl-related-keys.c
index 3a34df7..d6e1d61 100644
--- a/src/data/grl-related-keys.c
+++ b/src/data/grl-related-keys.c
@@ -471,7 +471,7 @@ grl_related_keys_get_boolean (GrlRelatedKeys *relkeys,
 {
   const GValue *value;
 
-  g_return_val_if_fail (GRL_IS_RELATED_KEYS (relkeys), NULL);
+  g_return_val_if_fail (GRL_IS_RELATED_KEYS (relkeys), FALSE);
 
   value = grl_related_keys_get (relkeys, key);