[grilo] core: Fix memory leak in get_additional_sources

[Bastien Nocera <hadess src gnome org>]

commit 6329e1be0d3e585ccbdf5d6fbf416c15ce6f93f4
Author: Sebastian Keller <sebastian-keller gmx de>
Date:   Thu Feb 12 17:43:51 2015 +0100

    core: Fix memory leak in get_additional_sources
    
    missing_in_data creates a new list which was not being freed by
    get_additional_sources.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=744408

 src/grl-source.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/grl-source.c b/src/grl-source.c
index 061f45b..f07b7ce 100644
--- a/src/grl-source.c
+++ b/src/grl-source.c
@@ -1426,6 +1426,7 @@ get_additional_sources (GrlSource *source,
                  GRL_METADATA_KEY_GET_NAME (key));
     }
   }
+  g_list_free (missing_keys);
 
   /* list_union() is used to remove doubles */
   return list_union (NULL, result, NULL);