Prevent potential infinite outbound authentication loops in registration.

Prior to this patch, Asterisk would always respond to 401 responses to
registration attempts by trying to provide a registration with authentication
credentials. Even if subsequent attempts were rejected with 401 responses,
Asterisk would continue this behavior. If authentication credentials were
incorrect, this could continue forever.

With this patch, we keep track of whether we have attempted authentication
on an outbound registration attempt. If we already have, we don not try
again until the next attempt. This prevents the infinite loop scenario.

Review: https://reviewboard.asterisk.org/r/4273



git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@429761 f38db490-d61c-443f-a65b-d21fe96a405b
res_pjsip_sdp_rtp: wrong bridge chosen when the DTMF mode is not compatible

A native rtp bridge was being chosen (it shouldn't have been) when using two
pjsip channels with incompatible DTMF modes.  This patch sets the rtp instance
property, AST_RTP_PROPERTY_DTMF, for the appropriate DTMF mode(s) for pjsip.
It was not being set before, meaning all DTMF modes for pjsip were being treated
as compatible, thus native bridging would be chosen as the bridge type when it
shouldn't have been.

ASTERISK-24459 #close
Reported by: Yaniv Simhi
Review: https://reviewboard.asterisk.org/r/4265/


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@429763 f38db490-d61c-443f-a65b-d21fe96a405b