One of the advantages is that LIBVIRT_RESULT aligns the resulting
message for us.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
LIBVIRT_ARG_WITH_ALT is more generic than LIBVIRT_ARG_WITH, which
is tailored at switching features on and off.
Rename the macros according to their intended purpose, and add
some documentation to help developers pick between the two.