chan_dahdi/SS7: Made reject incoming call for an in-alarm or blocked channel.

chan_dahdi/SS7: Made reject incoming call for an in-alarm or blocked channel.

If a SS7 call comes in requesting a CIC that is in-alarm, the call is
accepted and connects if the extension exists in the dialplan.  The call
does not have any audio.

* Made release the call immediately with circuit congestion cause.

(closes issue ASTERISK-20204)
Reported by: Tuan Le
Patches:
      jira_asterisk_20204_v1.8.patch (license #5621) patch uploaded by rmudgett
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Merged revisions 376058 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 376059 from http://svn.asterisk.org/svn/asterisk/branches/10

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@376060 65c4cc65-6c06-0410-ace0-fbb531ad65f3