Forget last daemon/ dir artefacts

Forget last daemon/ dir artefacts

The most important part is LIBVIRTD_PATH env var fix. It is used
in virFileFindResourceFull() from tests. The libvirtd no longer
lives under daemon/.

Then, libvirtd-fail test was still failing (as expected) but not
because of missing config file but because it was trying to
execute (nonexistent) top_builddir/daemon/libvirtd which
fulfilled expected outcome and thus test did not fail.

Thirdly, lcov was told to generate coverage for daemon/ dir too.

Fourthly, our compiling documentation was still suggesting to run
daemonn/libvirtd.

And finally, some comments in a systemtap file and a probes file
were still referring to daemon/libvirtd.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>