Ensure after-bridge behavior is correct when moving from Stasis to a non-Stasis bridge.

Ensure after-bridge behavior is correct when moving from Stasis to a non-Stasis bridge.

Because of the departable state of channels that enter Stasis bridges, Stasis has to
take responsibility for directing the channel to its intended after-bridge destination
if the channel moves from a Stasis bridge to a non-Stasis bridge. This change ensures
that when such a move occurs, when the channel leaves the bridging system, any after
bridge gotos are honored.

Review: https://reviewboard.asterisk.org/r/3920
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Merged revisions 421792 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 421794 from http://svn.asterisk.org/svn/asterisk/branches/13

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@421795 65c4cc65-6c06-0410-ace0-fbb531ad65f3