Fix a SIP request memory leak with TLS connections.

Fix a SIP request memory leak with TLS connections.

During the TLS re-work in chan_sip some TLS specific code was moved
into a separate function. This function operates on a copy of the
incoming SIP request. This copy was never deinitialized causing a
memory leak for each request processed.

This function is now given a SIP request structure which it can use
to copy the incoming request into. This reduces the amount of memory
allocations done since the internal allocated components are reused
between packets and also ensures the SIP request structure is
deinitialized when the TLS connection is torn down.

(closes issue ASTERISK-20763)
Reported by: deti
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Merged revisions 377257 from http://svn.asterisk.org/svn/asterisk/branches/1.8

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@377258 65c4cc65-6c06-0410-ace0-fbb531ad65f3