qemu introduced these options in 2eb1cd0768 ("s390x: CPACF: Handle key
wrap machine options") released in qemu-v2.3.0 but was exposed in
query-command-line-options only in 5bcfa0c543 ("util/qemu-config: fix
missing machine command line options").
The problem is that they are exposed even for architectures which don't
actually in fact support those.
Make the two capabilities a bit more useful by assuming them only on
s390 and thus removing them from other arches.
Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>