IuUP->AMR: do not patch payload type a second time

When converting IuUP to AMR/RTP, bridge_iuup_to_rtp_peer() sets the AMR
side's payload type number and then calls mgcp_send(). In mgcp_send(),
do not attempt to patch the payload type number a second time.

In mgcp_send(), skip patching payload type numbers if the source side is
IuUP. This matches exactly the case of converting IuUP to AMR/RTP.

There already is a check for IuUP, but for the wrong side. Drop that one
and explain in a comment why.

Move the comment about transcoding into the failure branch, where it is
relevant and doesn't clutter the new explanation of payload type
patching conditions.

Related: OS#5720
Related: SYS#5092
Change-Id: I7c722cd959f76bd104ae4941d182c77e5c025867
1 file changed