The guestfs_selinux_relabel function was very hard to use. In
particular it didn't just do an SELinux relabel as you might expect.
Instead you have to write a whole bunch of code around it (example[1])
to make it useful.
Another problem is that it doesn't let you pass multiple paths to the
setfiles command, but the command itself does permit that (and, as it
turns out, will require it). There is no backwards compatible way to
extend the existing definition to allow a list parameter without
breaking API.
So deprecate guestfs_selinux_relabel. Reimplement it as
guestfs_setfiles. The new function is basically the same as the old
one, but allows you to pass a list of paths. The old function calls
the new function with a single path parameter.
[1] https://github.com/libguestfs/libguestfs-common/blob/master/mlcustomize/SELinux_relabel.ml
Before this change the tests ran in about 12m34 and afterwards in
about 6m20, although the real change is more dramatic if you only run
tests from the tests/ subdirectory (as language tests still run serially).
This breaks valgrinding for now, which I intend to fix properly later.
test-relabel.pl performs a full SELinux relabelling of the phony guest,
and the selinux_relabel API does not work if the "selinuxrelabel"
feature is not available.
