https://bugzilla.redhat.com/show_bug.cgi?id=1710575

It may happen that the system where libvirt is built at doesn't
have udevadm binary but the one where it runs does have it.
If we change how udevadm is run in virWaitForDevices() then we
can safely pass a default value in m4 macro.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

The udevsettle binary is no longer used anywhere as it was
replaced by 'udevadm settle'. There's no reason for us to even
check for it in configure.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

We already require libxml to be installed, so it is not unreasonable
to require xmllint and xsltproc to be installed too - any platform
with the former will have the latter too.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

The HTML pages are currently validated against an XHTML 1.0 DTD.
This makes it impossible to take advantage of features that are
introduced in HTML 5, because they'll fail validation.

There is intentionally no DTD defined for HTML 5, so there's no
alternative to XHTML 1.0 DTD that we could switch to. The only
options are to stick with XHTML 1.0 forever, or drop the DTD
validation, and we pick the latter.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Signed-off-by: NPavel Hrdina <phrdina@redhat.com>