Changes

debian: prepare for more subpackages

Prepare to add these subpackages in follow-up patches:
* osmocom-bb-trx-toolkit
* osmocom-bb-trxcon
* osmocom-bb-virtphy

We need these components to run some of the ttnc3 testsuites. By having
them packaged, we can just install them from the binary repositories
along with the SUT.

trxcon and virtphy are autootols based, so rework debian/rules to
support building multiple autotools projects.

Related: https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/38851/1..2//COMMIT_MSG#b9
Change-Id: I77ad988f5405e6fa9e585eeb646e513ac7d92485

debian: add subpackage osmocom-bb-trxcon

Change-Id: I548cec7427d70706b1b477c0845234efe6cf825f

debian: add subpackage osmocom-bb-virtphy

I've decided to name the package osmocom-bb-virtphy so there is no
underscore in it (would look weird in addition to the minus character)
and because it matches the name of the binary "virtphy".

Change-Id: I09d98aba81ab6c76ad46aae36e7369114cef7dd7

debian: add subpackage osmocom-bb-trx-toolkit

Change-Id: I3d8140991afaf08b6fff0e80d45dd0310c98ea30