Prevent a crash on outbound SIP MESSAGE requests.

Prevent a crash on outbound SIP MESSAGE requests.

If a From header on an outbound out-of-call SIP MESSAGE were
malformed, the result could crash Asterisk.

In addition, if a From header on an incoming out-of-call SIP
MESSAGE request were malformed, the message was happily accepted
rather than being rejected up front. The incoming message path
would not result in a crash, but the behavior was bad nonetheless.

(closes issue ASTERISK-22185)
reported by Zhang Lei

git-svn-id: https://origsvn.digium.com/svn/asterisk/certified/branches/1.8.15@397253 65c4cc65-6c06-0410-ace0-fbb531ad65f3