Linux: RedHat packaging updates for RHEL6

Linux: RedHat packaging updates for RHEL6

Update our bundled spec file and related tools so they can be used
to build OpenAFS on the RHEL6 beta.

- Make kmodtool recognise el6 as having "modern" kernel naming
  conventions
- Replace %{PACKAGE_VERSION} (which seems to have disappeared)
  with the standard %{version} macro

Thanks to billings and phalenor on IRC for their testing efforts.

Reviewed-on: http://gerrit.openafs.org/1806
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 0d0e7699c9f789214205fe6837cded1a4c95f9c0)

Reviewed-on: http://gerrit.openafs.org/2638
Tested-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 41040638e23be43e260f79a4694df528244ef38b)
Change-Id: Ia2d1d1c377d7df0a4e7bdd22ac5f86c7253ffa66
Reviewed-on: http://gerrit.openafs.org/3515
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>