libosmo-mgcp doesn't properly deal with SDP containing multiple codecs
libosmo-mgcp has a SDP parser that can deal with a rtpmap of up to 8 different codecs, but then only passes two of them up in the parsed data structure, see
This needs to change to make sure that the full list of codecs is parsed + passed into the actual MGW codebase, so the MGW can make an educated choice between the codecs.
As a peperation I have cleaned up the existing codec selection. There is a codec and an alt_codec struct memeber. The codec is the primary field which is actually used in the code. However, alt_codec is not used at all. I have removed this alt_codec field now.
https://gerrit.osmocom.org/#/c/osmo-mgw/+/9234 sdp: remove unused alt_codec field from struct mgcp_rtp_end