This partially revert 0454cf05d3.
The executable actually does not work with itself, but needs to be
combined with test-udev.py. But, even so, the executable is for testing.
In the next commit, test and normal executables are declared in the same
way, and naming of the executable becomes essential to classify them.
Let's rename the executable and prefix with 'test-'.
Containers generally don't have permission to mknod() which is
required by test-udev so let's skip the test as well if we detect
we're running in a container.
As part of the build, we would populate build/test/sys/ using
sys-script.py, and then udev-test.p[ly] would create a tmpfs instance
on build/test/tmpfs and copy the sys tree to build/test/tmpfs/sys.
Also, we had udev-test.p[ly] which called test-udev. test-udev was
marked as a manual test and installed, but neither udev-test.p[ly] or
sys-script.py were.
test-udev is renamed to udev-rule-runner, which reduces confusion and
frees up the test-udev name. udev-test.py is renamed to test-udev.py.
All three files are now installed.
test-udev.py is modified to internally call sys-script.py to set up the
sys tree. Copying and creating it from scratch should take the same
amount of time. We avoid having a magic directory, everything is now
done underneath a temporary directory.
test-udev.py is now a normal installed test, and run-unit-tests.py will
pick it up. When test-udev.py is invoked from meson, the path to
udev-rule-runner is passed via envvar; when it is invoked via
run-unit-tests.py or directly, it looks for udev-rule-runner in a relative
path.
The goal of this whole change is to let Debian drop the 'udev' test.
It called sys-script.py and udev-test.pl from the source directory and
had to recreate a bunch of the logic. Now test-udev.py will now be called
via 'upstream'.
