Fixes a regression introduced in
fa67d56541 whereby elogind would fail to
start with:
Cannot determine cgroup we are running in: No data available
Out of memory.
thereby preventing log-in altogether.
* gnu/packages/freedesktop.scm (elogind)[arguments]: Pass
"--with-cgroup-controller=elogind".
* gnu/tests/desktop.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.