[rygel] core: Do not serialize empty date

[Jens Georg <jensgeorg src gnome org>]

commit bf6b494360faba6c145d667c5cfecdb34851f76e
Author: Jens Georg <mail jensge org>
Date:   Tue Oct 11 19:44:49 2011 +0200

    core: Do not serialize empty date

 src/rygel/rygel-media-item.vala |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/src/rygel/rygel-media-item.vala b/src/rygel/rygel-media-item.vala
index dd3ddcf..44eb68f 100644
--- a/src/rygel/rygel-media-item.vala
+++ b/src/rygel/rygel-media-item.vala
@@ -195,7 +195,10 @@ public abstract class Rygel.MediaItem : MediaObject {
 
         didl_item.title = this.title;
         didl_item.upnp_class = this.upnp_class;
-        didl_item.date = this.date;
+
+        if (this.date != null) {
+            didl_item.date = this.date;
+        }
 
         /* We list proxy/transcoding resources first instead of original URIs
          * because some crappy MediaRenderer/ControlPoint implemenation out