AST-2014-016: Fix crash when receiving an in-dialog INVITE with Replaces in res_pjsip...

AST-2014-016: Fix crash when receiving an in-dialog INVITE with Replaces in res_pjsip_refer.

The implementation of INVITE with Replaces in res_pjsip_refer did not expect them to
occur in-dialog. As a result it would incorrectly attempt to hang up a channel it
thought was under its control. In reality the channel would be under the control of
another thread. When the other thread accessed the channel it would be accessing freed
memory and could crash.

This change makes res_pjsip_refer not act on an in-dialog INVITE with Replaces.

ASTERISK-24528 #close
Reported by: Joshua Colp
........

Merged revisions 428304 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@428305 65c4cc65-6c06-0410-ace0-fbb531ad65f3