rpm: Build srpms without %dist in their name

rpm: Build srpms without %dist in their name

On RHEL6, %dist is set for all RPMS and SRPMS built on the system. This
leads to makesrpm.pl building SRPMS with .el6 in their release. As we
endeavour to use the same SRPM on all of our Fedora platforms, this is
less than ideal, so change makesrpm.pl to squash the setting of %dist
before building the RPM.

Change-Id: I5b5b9db7654ce21a269233e8950d4f4d1df81ad7
Reviewed-on: http://gerrit.openafs.org/4285
Reviewed-by: Alexander Ivan Redinger <aredinger@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>