Fix determination of locally bound IP for RTP sockets
Fix determination of locally bound IP for RTP sockets

After we create a socket and bind it to INADDR_ANY, we cannot yet use
getsockname() to resolve the locally bound IP.  This only works after
the socket has been connected to the remote IP.  So we have to move the
osmo_rtp_get_bound_ip_port() to a code section after
osmo_rtp_socket_connect() has already happened.

With the code prior to this commit, unless "rtp bind-ip" was used in the
config file, we reported "0.0.0.0" as the "Source IP AddresS" in the IPA
CRCX ACK to the BSC.   This is of course wrong, as the BSC will then use
this "0.0.0.0" as destination address for the incoming RTP stream :(

Please note that for this fix to work, you also need a libosmoabis.git
with commit d426d458ca96ba29793e35b1b2a73fbcb3b2c888 which actually
causes osmo_rtp_socket_connect() to actually issue connect() on the
socket at all.

osmocom/osmo-bts,telenoobie/osmo-bts,osmocom/osmo-bts,geosphere/osmo-bts,geosphere/osmo-bts,osmocom/osmo-bts,telenoobie/osmo-bts,geosphere/osmo-bts,shimaore/osmo-bts,geosphere/osmo-bts,telenoobie/osmo-bts,telenoobie/osmo-bts,shimaore/osmo-bts,shimaore/osmo-bts,shimaore/osmo-bts