Changes

mgw: Validate CallID before updating endp->x_osmo_ign

This allows already starting to mark a clear line in CRCX handling
function between *read-only parsing + validation* and *read-write
allocation and update* of objects.

This in turn will allow further clean up on the second mentioned step.

Change-Id: Ia41f7383171bb24f48297456935c633536aa7b05

mgw: Delay osmux trunk setup to point where it is really needed

This way code is simplified by putting all osmux code together.

Change-Id: I27f7355ee99f1781fc2034a23c7cca756fb203d2

mgw: Store Command as enum in struct mgcp_request_data

This simplifies code further, and will simpify more code since we'll
have some easy way to check for the command we are in during a request.

Change-Id: I2d4b5ddb93376b59413b34c9668c41157ab05497

mgw: Move struct mgcp_request_data definition to header file

All the related handling structs are placed in the header file, let's
move them there. This will also allow accessing the rq object
information in other files.

Change-Id: I1b2831874c1aaad054ad19bf87646062ba9d4da4

mgw: Move cfg pointer from pdata to rq

The externa object context is held in rq object, not in pdata object,
which holds parsed msg state only.

Change-Id: Ie64fb6250cc84f1e7737b5c1cf5cca314c7020ed

mgw: Add backpointer from pdata to req to have context available

This will also allow eg. parsing/validating differently based on the
command being parsed, or incrementing rate counters per cmd group.

Change-Id: I464258ca1a8817d58ae5c5426dfc3b7cee6763d3

mgw: Use tall_mgw_ctx to allocate struct mgcp_config

Change-Id: Ib51f1066bb73da4472bd8967cc1b1c44e964e9e5

mgw: Allocate req and pdata with talloc

This will allow allocating parsed objects as child of the request and
make sure they are freed after handling the request finishes.
Change-Id: I2b971d0c8268f4c0a30b84b54a2e5f16ada4ecdb