Restore call progress code for analog ports.

Extracting sig_analog from chan_dahdi lost call progress detection
functionality.

* Fix analog ports from considering a call answered immediately after
dialing has completed if the callprogress option is enabled.

(closes issue ASTERISK-18841)
Reported by: Richard Miller
Patches:
      chan_dahdi.diff (license #5685) patch uploaded by Richard Miller (Modified by me)
      sig_analog.c.diff (license #5685) patch uploaded by Richard Miller (Modified by me)
      sig_analog.h.diff (license #5685) patch uploaded by Richard Miller
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Merged revisions 347006 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 347007 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@347008 65c4cc65-6c06-0410-ace0-fbb531ad65f3