Not all distros support booting without an initrd. E.g. the Debian
kernel builds ext4 as a module and so relies on an initrd to
successfully start the QEMU-based images.
This catches errors like "ninja not found", missing programs etc. early,
instead of silently ignoring them and trying to boot a broken VM.
In install_config_files(), allow some distro specific files to be absent
(such as /etc/sysconfig/init).
All test/TEST* but TEST-02-CRYPTSETUP share the same check_result_qemu()
and test_cleanup(), so move them into test_functions and only override
them in TEST-02-CRYPTSETUP.
Also provide a common test_run() which by default assumes that both QEMU
and nspawn tests are run. Particular tests which don't support either
need to explicitly opt out by setting $TEST_NO_{QEMU,NSPAWN}. Do it this
way around to avoid accidentally forgetting to opt in, and to encourage
test authors to at least always support nspawn.
Automatic rebuilding is removed: it doesn't play well with ninja, because
ninja always writes logs, and even if nothing needs to be built, it will
make the log file owned by root. So let's just remove this, and say that
the user must always do the build first.
I'm also keeping make for the tests, because ninja doesn't play well with
sudo.
Since the build directory is arbitrary, it needs to be specified, e.g.
sudo make BUILD_DIR=/home/zbyszek/src/systemd/build1 -C test/TEST-01-BASIC/
Michael Biebl