on some systems, tests may take over an hour to run--only to find
you might have used an unintended Meson version (e.g. release instead
of dev). This change prints the Meson version at the start of the
run_*tests*.py scripts.

Also, raise SystemExit(main()) is preferred in general over
sys.exit(main())

Currently, colourize_console is a constant, set at process
initialization.

To allow the actual stdout to be easily compared with the expected when
running tests, we want to allow colourization to be on for the test
driver, but not for the in-process configure done by run_configure,
which has stdout redirected from a tty to a pipe.

v2:
Cache _colorize_console per file object

v3:
Reset cache on setup_console()

A current rather untyped storage of options is one of the things that
contributes to the options code being so complex. This takes a small
step in synching down by storing the compiler options in dicts per
language.

Future work might be replacing the langauge strings with an enum, and
defaultdict with a custom struct, just like `PerMachine` and
`MachineChoice`.

This is more correct, and forces the target(s) to be rebuilt if the
PDB files are missing. Increases the minimum required Ninja to 1.7,
which is available in Ubuntu 16.04 under backports.

We can't do the same for import libraries, because it is impossible
for us to know at configure time whether or not an import library will
be generated for a given DLL.

Pull the crossfile specification out of run_test.py so it can be
specified in the CI job configuration.

Also make some fixes to output ordering in run_test.py.

`get_backend_commands()` doesn't get called when we run tests as
subprocesses, so detect ninja on import. This should speed up CI.

Fixes https://github.com/mesonbuild/meson/issues/5888