Change "mdadm --run" to use the same code as "mdadm --IRs".

Current "mdadm --run /dev/mdX" will not handle external metadata
properly.  mdmon won't be started etc.

So use the code from "mdadm -IRs" instead - that already does all
the right things.

Reported-by: Francis Moreau <francis.moro@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Add raid6check to .gitignore

Signed-off-by: NeilBrown <neilb@suse.de>
Add ANNOUNCE-3.2.6 from different branch

just for completeness...

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