LU-278 build: Only warn for tag/version mismatch

LU-278 build: Only warn for tag/version mismatch

The configure process should NOT abort just because the most
recent tag is not of the form that upstream uses to tag Lustre.
Downstream developers may use their own tags, or just add
extensions to upsteam's version tags.

Change-Id: I9a98bfd4475d3df2694f536ba0352779a62650c7
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/510
Tested-by: Hudson
Reviewed-by: Brian J. Murrell <brian@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>