GSUP: add inter-MSC handover related msgs and IEs

Based on a draft created by Neels, which is the result of reading a MAP
trace of two MSCs negotiating inter-MSC handovers, and of reading the
TS 29.002, TS 29.010 and related specs:
https://lists.osmocom.org/pipermail/openbsc/2019-January/012653.html

I figured out that the "Handover Number" mentioned in the specifications
is the same as the MSISDN IE that we already have, so we can use that
instead of creating a new IE (example usage in tests/gsup/gsup_test.c).

Create a new OSMO_GSUP_MSGT_E_ROUTING_ERROR message type, which the GSUP
server uses to tell a client that its message could not be forwarded to
the destination (see [1]). MAP has no related message.

[1]: Change-Id: Ia4f345abc877baaf0a8f73b8988e6514d9589bf5 (osmo-hlr.git)

Related: OS#3774
Change-Id: Ic00b0601eacff6d72927cea51767801142ee75db

0 files changed, 0 insertions, 0 deletions