LU-10070 lod: SEL: Layout sanity checking

LU-10070 lod: SEL: Layout sanity checking

Add layout sanity checking for self-extending layouts.

This requires a more complex method checking layouts,
checking the entire layout rather than just individual
components against their immediate neighbors.  This is
implemented with a layout sanity callback which walks the
layout.

Incorporate mirror sanity checks from lfs.c.

Cray-bug-id: LUS-2528
Signed-off-by: Patrick Farrell <paf@cray.com>
Change-Id: I960a4ce96ace54f7fe4305b9197e27c540f81211
Reviewed-on: https://review.whamcloud.com/33784
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>