Increment version for clustered bitmaps

Increment version for clustered bitmaps

Add BITMAP_MAJOR_CLUSTERED as 5, in order to prevent older kernels
to assemble a clustered device.

In order to maximize compatibility, the major version is set to
BITMAP_MAJOR_CLUSTERED *only* if the bitmap is clustered.

Also, added MD_FEATURE_CLUSTERED in order to return error
for older kernels which would assemble MD in case bitmap is
corrupted.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>