md: allow a resync that is waiting for other resync to complete, to be aborted.

md: allow a resync that is waiting for other resync to complete, to be aborted.

If two arrays share a device, then they will not both resync at the
same time.  One will wait for the other to complete.
While waiting, the MD_RECOVERY_INTR flag is not checked so a device
failure, which would make the resync pointless, does not cause the
resync to abort, so the failed device cannot be removed (as it cannot
be remove while a resync is happening).

So add a test for MD_RECOVERY_INTR.

Reported-by: Brett Russ <[email protected]>
Signed-off-by: NeilBrown <[email protected]>