RedHat packaging: Use %{dist} not %{osver}

RedHat packaging: Use %{dist} not %{osver}

There's a standard mechanism for defining a RPMs target
distribution in the Fedora and RedHat worlds. This is to use the
%{dist} macro, and to insert it at the end (not the beginning) of
the release field.

Move over to using this standard mechanism, and modify the build
system to match. Note that this means that RPM names have now
changed slightly.

Reviewed-on: http://gerrit.openafs.org/3981
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 2b094cae6c39bc9e2d8f23f4654e137876b25d57)

Change-Id: I764a91e787acb2d2e3d0595cb344bc5b44465bd9
Reviewed-on: http://gerrit.openafs.org/3984
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>