LU-10070 lod: SEL: Repeated components

LU-10070 lod: SEL: Repeated components

This changes behavior when there is no next component to
spill over to.  Currently, in that case, we just extend
the current component regardless of available space.

Now, if there is no following component, we try repeating
the current component, creating a new component using the
current one as a striping template.  We try assigning
striping for this component.  If there is sufficient free
space on the OSTs chosen for this component, it is
instantiated and i/o continues there.

If there is not sufficient space on the OSTs chosen for the
new component, we remove it & extend the current component.

This is a behavioral improvement, with no implications for
layout sanity checking.

Cray-bug-id: LUS-2528
Signed-off-by: Patrick Farrell <paf@cray.com>
Change-Id: If9f364b4105a4bb892dfe673c724e04781c46336
Reviewed-on: https://review.whamcloud.com/33786
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>