Podcast feed update status fixes
- podcast: make feed status 'updating' as transient status
This is primarily needed for handling feed update cancellations during rhythmbox close, as there is no definite timeline from plparser on how quickly it will detect the cancellation and invoke the user callback. So, rather than waiting / blocking for plparser callback during rhythmbox close, we make the feed 'updating' status as transient.
- podcast: update feed status on feed update cancellation