LU-1199 build: Increase ldiskfs version to 4.1.0

The ldiskfs version number has not changed in quite some time.

This brings the versioning in line with what LLNL has been using
externally, and allows us to realign on the same code.

Add an explicit requirement for "lustre-ldiskfs >= 4.1.0"
to the lustre spec file at the same time.

Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>
Change-Id: I72c9f52093942d881ee02dad8f65c2f04dbef35e
Reviewed-on: http://review.whamcloud.com/5938
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>