This new keyword argument makes it possible to run specific
test setups only on a subset of the tests. For example, to
mark some tests as slow and avoid running them by default:
add_test_setup('quick', exclude_suites: ['slow'], is_default: true)
add_test_setup('slow')
It will then be possible to run the slow tests with either
`meson test --setup slow` or `meson test --suite slow`.
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