This matches `meson test`, and there's really no other meaning that
could be attributed to this, since you would call `meson` to get the
version, not the `compile` sub-command.
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082
With this running `meson compile` inside the builddir actually works,
and you don't have to do `meson compile -C .`
Clearly this was the intent since the option already has `default='.'`