musiconhold: Add preferchannelclass=no option to prefer app class.

The new option 'preferchannelclass' is added to musiconhold.conf. If yes
(the default) the CHANNEL(musicclass) is preferred when choosing the
hold music. If it is no, the class suggested by the application that
calls the MoH (e.g. the Queue() app) gets preferred (new behaviour).

This way you set a different hold-music from the Queue-music by setting
both the CHANNEL(musicclass) and the queue-context musicclass.

ASTERISK-24276 #close
Reported by: Kristian Høgh
Patches:
  app_override_channel_moh.patch uploaded by Kristian Høgh (License #6639)

Review: https://reviewboard.asterisk.org/r/4010/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@423893 f38db490-d61c-443f-a65b-d21fe96a405b
res_pjsip.c: Add missing off nominal cleanup in ast_sip_push_task_synchronous().

* Made memset the std struct in ast_sip_push_task_synchronous() because if
DEBUG_THREADS is enabled then uninitialized lock tracking data is used.
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Merged revisions 423894 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 423895 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@423896 f38db490-d61c-443f-a65b-d21fe96a405b