RedHat: support building on ELRepo kernels

Amend the pattern matching in openafs-kmodtool to support
building for kernels from ELRepo.

Reviewed-on: http://gerrit.openafs.org/10083
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 397a086b77c4351e5332a73ae4859faf239bf45e)

Change-Id: I0f1a7126271cb7952e4369af3c93484c4b0567d0
Reviewed-on: http://gerrit.openafs.org/10703
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>