Assemble imsm spares in matching domain only

Assemble imsm spares in matching domain only

Imsm spare will only be taken if it matches domain of
identified members of currently assembled array.

This implies that:
- spare with null domain will match first array assembled.
- if array has null domain then no spare will match

If we allow spares to set st they may block assembly of subarrays.
This is because in auto-assembly tmpdev->used=0 for a spare not matching
any array. If we find such spare before container and set st, the content
will not get assembled.

We allow uuid_zero match any uuid in assembly as unsuitable spares will
be rejected on domain check.

Signed-off-by: Anna Czarnowska <anna.czarnowska@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>