Usage of AC_REQUIRE will mess with order how LIBVIRT_CHECK_* macros
are composed into configure.ac.  This ensures that the output of
configure --help is properly ordered and grouped into sections.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Following patch will update LIBVIRT_CHECK_(LIB|LIB_ALT|PKG) macros in
a way that you will be able to call a another macro as a fallback if
the first one fails.  To allow that, we need to move the
LIBVIRT_ARG_WITH out of those macro to not have two or more same lines
in output of "configure --help".
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Running the output of qemu -help doesn't make any sense.  We should be
looking for libvirt being mentioned in the output.  This worked by
accident, let's make it work as expected it to.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>