ARI: Fix a crash caused by hanging during playback to a channel in a bridge

ASTERISK-24147 #close
Reported by: Edvin Vidmar
Review: https://reviewboard.asterisk.org/r/3908/
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Merged revisions 421879 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@421880 f38db490-d61c-443f-a65b-d21fe96a405b
Fix a locking inversion in MixMonitor.

We need to unlock the audiohook before trying to lock
the channel, since the correct locking order is channel
then audiohook.



git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@421882 f38db490-d61c-443f-a65b-d21fe96a405b