We don't want to pacakge osmo-bsc_nat from osmo-bsc.git at this
point yet. It only suports SCCPlite, which is not yet fully supported
by osmo-bsc.
Rather, we continue to package osmo-bsc_nat from openbsc.git like we did
so far.
Also, the osmo-bsc_nat binary really doesn't belong into the osmo-bsc
package at all.
Change-Id: Icf0bf80d61141ec060b6d2efcf3e65e2ef1ac2d6