Meson internally knows about many languages and tools, and *FLAGS
variables, and which languages to use them for. Instead of duplicating
this logic, import it from mesonbuild.*
This logic was originally standalone, but now that it is merged into the
Meson tree we can have a single source of truth.
This reverts commit e257a870fe.
The PR adding this command had infinitely hanging CI, and now that it is
merged to master we cannot get any CI on any PR to succeed.