Detail: differentiate between container and inactive arrays

Detail: differentiate between container and inactive arrays

Containers used to be handled as active arrays because GET_ARRAY_INFO
ioctl returns valid structure for them. As containers appear as inactive
in sysfs, the output for detail command has changed.

Stop relying on inactive state for containers. Make the output look the
same as in mdadm 4.0.

Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>