[rygel-gst-0-10-plugins] Remove an assertion.

[Krzesimir Nowak <krnowak src gnome org>]

commit 0476837fca40f3c634accb62c01e5ff5ce7cff4c
Author: Krzesimir Nowak <krnowak openismus com>
Date:   Wed Feb 6 14:01:30 2013 +0100

    Remove an assertion.
    
    Callback may be NULL here and both recursive file monitor and
    harvesting task indeed pass NULL here.

 .../rygel-media-export-recursive-file-monitor.c    |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/src/media-export/rygel-media-export-recursive-file-monitor.c b/src/media-export/rygel-media-export-recursive-file-monitor.c
index 6650b3c..7d2704e 100644
--- a/src/media-export/rygel-media-export-recursive-file-monitor.c
+++ b/src/media-export/rygel-media-export-recursive-file-monitor.c
@@ -203,7 +203,6 @@ void rygel_media_export_recursive_file_monitor_add (RygelMediaExportRecursiveFil
 
   g_return_if_fail (self);
   g_return_if_fail (file);
-  g_return_if_fail (callback);
 
   /* Setup the async result.
    */