[rygel] media-export: Fix album art for m4a files

[Jens Georg <jensgeorg src gnome org>]

commit e8c8498b40cc1a396521679c4ed5afc4fd3dce1d
Author: Jens Georg <mail jensge org>
Date:   Sun Jun 15 11:51:22 2014 +0200

    media-export: Fix album art for m4a files
    
    The tag is PREVIEW_IMAGE in that case, not IMAGE
    
    Signed-off-by: Jens Georg <mail jensge org>

 .../rygel-media-export-item-factory.vala           |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/plugins/media-export/rygel-media-export-item-factory.vala 
b/src/plugins/media-export/rygel-media-export-item-factory.vala
index c188337..ae71f40 100644
--- a/src/plugins/media-export/rygel-media-export-item-factory.vala
+++ b/src/plugins/media-export/rygel-media-export-item-factory.vala
@@ -274,6 +274,10 @@ namespace Rygel.MediaExport.ItemFactory {
         Sample sample;
         tags.get_sample (Tags.IMAGE, out sample);
         if (sample == null) {
+            tags.get_sample (Tags.PREVIEW_IMAGE, out sample);
+        }
+
+        if (sample == null) {
             store.add (item, file, null);
 
             return item;