In some tests, e.g. -f nixos/release.nix tests.simple.x86_64-linux
we use noXlibs and qemu.ga. Now that output is tiny but to get it
a full qemu build is done, and some dependencies like gtk3 won't build
with noXlibs due to their dependencies being too stripped down.
Therefore let's reduce qemu features in noXlibs case.
The `sdlSupport = false;` part probably wasn't needed,
but I added it for consistency.
Discovered via https://github.com/NixOS/nixpkgs/pull/82743 which
improved option checking, causing an evaluation error that was
hard to understand without running the evaluation manually.
symlinkJoin can break (silently) when the passed paths contain symlinks
to directories. This should work now.
Down-side: when lib/tmpfiles.d doesn't exist for some passed package,
the error message is a little less explicit, because we never get
to the postBuild phase (and symlinkJoin doesn't provide a better way):
/nix/store/HASH-NAME/lib/tmpfiles.d: No such file or directory
Also, it seemed pointless to create symlinks for whole package trees
and using only a part of the result (usually very small part).
Turns out lot of software (including Chromium) use bundled fontconfig
so we either need to wrap every one of those, or re-introduce the global unversioned config.
The latter is easier but weakens hermetic configs. But perhaps those are not really worth the effort.
Since systemd 243, docs were already steering users towards using
`journal`:
eedaf7f322
systemd 246 will go one step further, it shows warnings for these units
during bootup, and will [automatically convert these occurences to
`journal`](f3dc6af20f):
> [ 6.955976] systemd[1]: /nix/store/hwyfgbwg804vmr92fxc1vkmqfq2k9s17-unit-display-manager.service/display-manager.service:27: Standard output type syslog is obsolete, automatically updating to journal. Please update│······················
your unit file, and consider removing the setting altogether.
So there's no point of keeping `syslog` here, and it's probably a better
idea to just not set it, due to:
> This setting defaults to the value set with DefaultStandardOutput= in
> systemd-system.conf(5), which defaults to journal.
Since systemd 246, these are only installed by systemd if
HAVE_SYSV_COMPAT is true, which only is the case if you set
sysvinit-path and sysvrcnd-path (which we explicitly unset in the
systemd derivation for quite some time)
