codec: videotoolbox: don't restart on kVTVideoDecoderReferenceMissingErr
requested to merge ePirat/vlc:epirat-vt-no-restart-on-kVTVideoDecoderReferenceMissingErr into master
In f7434e60 I made this a non-critical error but after some more testing with a stream with a lot of missing references, it works fine when not restarting VideoToolbox fully when this happens and actually results in better playback.