qemu: capabilities: Add alternative detection of QEMU_CAPS_NUMA

qemu: capabilities: Add alternative detection of QEMU_CAPS_NUMA

'set-numa-node' is the command which can set the equivalent parameters
to '-numa' in preconfig mode, so we can use it as witness to see that
-numa is supported.

To ensure that the old detection method is removed once we'll be bumping
qemu support add a comment with the appropriate version check.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>