Fix an issue where Local channels dialed by app_queue are considered in use immediately.

The chan_local channel driver returns a device state of in use even if a created Local
channel has not yet been dialed. This fix changes the logic to return a state of not
in use until the channel itself has been dialed.

(closes issue ASTERISK-20390)
Reported by: tim_ringenbach

Review: https://reviewboard.asterisk.org/r/2116/
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Merged revisions 373878 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 373879 from http://svn.asterisk.org/svn/asterisk/branches/10
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Merged revisions 373880 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@373881 65c4cc65-6c06-0410-ace0-fbb531ad65f3