When cross-compiling, also report build machine compilers in the
compiler report produced by run_project_tests.py

Add a cross-file for MSVC UWP ARM64.

Bump cidata tag to get an updated install.ps1 script (run by run.ps1)
which sets the vcvars environment correctly when cross-compiling.

Since arranging the correct environment for simultaneous cross and
native 'cl' use is hard, this is test run uses '--cross-only' so we
don't require a native compiler.

Extend '--cross-only' so it also explicitly uses a machine file which
makes all build machine compilers unusable.

Add '--cross-only' option to run_tests.py, so we can arrange not to run
tests in the 'native' suite when only a cross-compiler is available, as
they can't succeed.

Split out tests (and parts of tests) which require a native compiler
from the 'common' suite to a new suite called 'native', so we can
selectively avoid running those tests when only a cross-compiler is
available.

Also move test '211 cmake module' to 'cmake' suite, since it appears
that the way we use cmake requires a native compiler.

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())

This makes the platform_fix_name() machinery for toolchains which don't
have gcc-like filename conventions available to cross testing.

I don't konw how the heck this has ever worked, but you know.

Add Azure pipelines CI

Use the 'CI' environment variable to detect CI environment, rather than a
collection of CI-specific ones.