[mythtv-cmyth] Workaround PVR lock on OSD

On playback OSD, PVR lock when AddTimer() returns other than PVR_ERROR_NO_ERROR.
I don't know the reason but i suspect a lock around notifications queue.
[cmyth] cmyth_rcv_free_inputlist: cmyth_rcv_ulong() sourceid failed (22)

Bail out when feedback is "EMPTY_LIST"
[mythtv-cmyth] Switch channel: Revert for reopening live stream

Free input list is always empty when recorder is locked even paused and we reopen the live stream anyway.
There is no other way since CHECK_CHANNEL() fails in some cases and could break the recorder and recording.
Merge branch 'cmyth_improvement' into local
Merge branch 'keep_live_rec_4' into local