Ensure that the Queue application tracks busy members in off nominal situations

Ensure that the Queue application tracks busy members in off nominal situations

There are a few code paths where the Queue application fails to count a paused
or in use queue member as being 'busy'.  This can cause callers to get stuck
in the Queue until a paused agent unpauses themselves.

(closes issue ASTERISK-20623)
Reported by: Bryan Walters
patches:
  app_queue.patch uploaded by Bryan Walters (license 5851)
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Merged revisions 375450 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 375451 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@375469 65c4cc65-6c06-0410-ace0-fbb531ad65f3