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 <bruss@netezza.com>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -6473,10 +6473,11 @@ void md_do_sync(mddev_t *mddev)
 		mddev->curr_resync = 2;
 
 	try_again:
-		if (kthread_should_stop()) {
+		if (kthread_should_stop())
 			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
 			goto skip;
-		}
 		for_each_mddev(mddev2, tmp) {
 			if (mddev2 == mddev)
 				continue;