configure.ac: remove --enable-osmo-bsc, --enable-nat

This is the OsmoBSC project.  Disabling the build of the BSC would be
somewhat odd, so let's remove the option.

Also, OsmoBSC depends on libosmo-sccp now, so we must unconditionally
depend on it.  As a result, we can remove the --enable-nat option,
as this was only to avoid a mandatory libosmo-sccp requirement in
historical times.

Change-Id: Icfee8a904d33b7c13ab8d185d64fb5c2337d8640
5 files changed