Add support for allowing an RTP engine to decide on whether it is possible for...

Add support for allowing an RTP engine to decide on whether it is possible for specific formats to be transcoded for an RTP instance.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@201902 65c4cc65-6c06-0410-ace0-fbb531ad65f3