Changes

build-old-tags: ignore failing due to api break

Ignore osmo-bsc and osmo-msc versions that are known to fail due to
intentional API break. osmo-bsc 1.12.2 and osmo-msc 1.12.2 build are
forward-compatible.

Note that previous releases don't need to be listed in tags_to_ignore()
as this script only builds the last 3 release tags.

Related: https://osmocom.org/news/284
Related: OS#6617
Change-Id: Ia9b3edeb369aac35b9baceaefdf517a4f3d532be