avviddec: really release frame at proper time

... by also removing it from the pending list of frames,
where it may still be in if it has never been submitted to _finish.
This could happen if is a decode-only frame, or in skipped decoding
situation, ...

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=693772
avviddec: discard unused input frames

... to avoid these piling up in list of pending frames.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=693772
avviddec: only use upstream framerate if really specified

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=704161
Update spec file with latest changes
avviddec: Use new gst_video_decoder_set_needs_format() API
avvidenc: plug input_state leak
Merge remote-tracking branch 'upstream/master' into ruih/master
Merge pull request #4 from cablelabs/merge-2013-12-09

Merge 2013 12 09