Use an async queue to prevent crashes in bvw_update_tags_dispatcher()
Use an async queue to prevent crashes in bvw_update_tags_dispatcher()

The BaconVideoWidget which called bvw_update_tags_dispatcher() could be
destroyed while the update is waiting in the idle queue. To fix this, we
change the tag update mechanism to use an async queue feeding a single idle
handler. The idle handler is removed when the BaconVideoWidget is destroyed.
Closes: bgo#628667

mediaserver2-plugins/totem-mediaserver2,mediaserver2-plugins/totem-mediaserver2