Merge pull request #606 in FS/freeswitch from ~MBRANCA/freeswitch:bugfix/FS-8565-txfax-fails-when-remote-party-changes to master

We've tested this with Yehavi and it does fix a problem that apparently happens a lot in the wild, and I have tested it against FS.

* commit 'd7b8394e':
  FS-8565 update initial rtp from address when auto changing port so we can avoid false later comparisons