there is no reason to check the channeltype of the channel calling SIPAddHeader

because it really only matters what the channeltype is of the *created* channel
in the subsequent dial (bug #4896)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6279 65c4cc65-6c06-0410-ace0-fbb531ad65f3