chan_dahdi/sig_analog: Fix distinctive ring detection to suck less.

chan_dahdi/sig_analog: Fix distinctive ring detection to suck less.

The distinctive ring feature interferes with detecting Caller ID and
appears to have been broken for years.  What happens is if you have a
ring-ring cadence as used in the UK you get too many DAHDI events for the
distinctive ring pattern array and Caller ID detection is aborted.  I
think when Zapata/DAHDI added the ring begin event it broke distinctive
ring.  More events happen than before and the code does no filtering of
which event times are recorded in the pattern array.

* Made distinctive ring only record the ringt count when the ring ends
instead of on just any DAHDI event.  Distinctive ring can be ring,
ring-ring, ring-ring-ring, or different ring durations for the up to three
rings.

* Fixed the distinctive ring detection enable (chan_dahdi.conf option
usedistinctiveringdetection) to be per port instead of somewhat per port
and somewhat global.  This has been broken since v1.8.

* Fixed using the default distinctive ring context when the detected
pattern does not match any configured dringX patterns.  The default
context did not get set when the previous call was a matched distinctive
ring pattern and the current call is not matched.  This has been broken
since v1.8.

* Made distinctive ring have no effect on Caller ID detection when it is
disabled.  Caller ID detection just monitors for 10 seconds before giving
up.

* Fixed leak of struct callerid_state memory when a polarity reversal
during Caller ID detection causes the incoming call to be aborted.

DAHDI-1143
AST-1545
ASTERISK-24825 #close
Reported by: Richard Mudgett

ASTERISK-17588
Reported by: Daniel Flounders

Review: https://reviewboard.asterisk.org/r/4444/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@432530 65c4cc65-6c06-0410-ace0-fbb531ad65f3