We expose a reason after the string 'MESON_SKIP_TEST', but it is
actually ignored when running the test, so it is only useful as
documentation and really might as well be a comment.
Make it even more useful by actually printing that string after the
'[SKIPPED]' message.
Also, sometimes a test can be skipped for multiple reasons, and it would
be useful to know which one occurred.
As a Meson developer it's often frustrating to have a single functional
test with a regression. These tests can be awkward to reproduce,
especially when they make use of a test.json file. This script provides
a simmple interface to call functional tests 1 at a time, regardless of
whether they use a test.json or not. If they do use a test.json, and
have a matrix, then the `--subtest` option can be used to select spcific
combinations, for example:
```sh
./run_single_test.py "test cases/frameworks/15 llvm" --subtest 1
```
will run only the second (zero indexed of course) subtest from the llvm
test cases.
This is not a super elegent script, but this is super useful.
Dylan Baker