Generate 'change' uevents when arrays change in non-obvious ways.

Generate 'change' uevents when arrays change in non-obvious ways.

When a 'container' gets started, we need udev to notice, but the
kernel has no way of knowing that a KOBJ_CHANGE event is needed.  So
send one directly via the 'uevent' sysfs attribute.

Also, uevents don't get generated when md arrays are stopped (prior to
2.6.28) so send 'change' events then too.

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