Support building the legacy openbsc source with osmo-build.dep.sh. This
will be used by the upcoming osmocom-build-old-tags-against-master.sh
script.
Related: OS#3765
Change-Id: I852e103e80bf295f692cf13c4cb38e80fbc19eca
Prepare for the upcoming osmocom-build-old-tags-against-master.sh
script, which will benefit from querying the last n git tags in advance.
Related: OS#3765
Change-Id: I61be4cffb9275cabc1b253f0b298503ad0d3aea4