[Libguestfs] SELinux relabeling: do it by default

[Richard W.M. Jones]

So I didn't realise that these commits break --selinux-relabel, eg:

$ rpm -q guestfs-tools
guestfs-tools-1.49.1-1.fc37.x86_64
$ virt-builder fedora-36 --selinux-relabel
virt-builder: unrecognized option '--selinux-relabel'
Try ‘virt-builder --help’ or consult virt-builder(1) for more information.

This is kind of bad since it breaks existing scripts.  We just had a
bug report about this from someone who is testing CentOS Stream 9.1
(where I backported the patches already).

This option should continue to exist, but do nothing.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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