contact header port ignored transport when using externip

This patch adds support for TCP/TLS in the Contact header when using
NAT, specifically externip or externhost. The original issue was that
Asterisk sent 5060 as the port in the contact header whether TLS was
used or not. Additionally, this patch adds 2 config options to sip.conf,
specifically externtcpport and externtlsport. This allows a user to
specify different external ports for TCP and TLS other than those used
internally, this is especially useful in in a PAT/port redirection setup.
Thanks to ebroad for reporting the issue and providing the patch!

(closes issue #15880)
Reported by: ebroad
Patches:
      portmap.patch uploaded by ebroad (license 878)
      externtXXport_v2.patch uploaded by ebroad (license 878)
Tested by: ebroad

Review: https://reviewboard.asterisk.org/r/392/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@222398 65c4cc65-6c06-0410-ace0-fbb531ad65f3