Older versions are not supported by the cmake module since 0.62.
This avoids having to hard-code the linux-bionic-gcc CI job as being
unable to run these tests, which leaves other older environments like
Debian 10 still trying to run them (and failing).
Signed-off-by: Simon McVittie <smcv@collabora.com>
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
Adds the `tools` section to `tests.json` to specify requirements
for the tools in the environment. All tests that fail at least
one tool requirements check are skipped.