spec hacks for vanilla and git-based kernel rpm builds

[Roland McGrath]

> Just wondering about the usesparse macro.  Any reason to conditionalize
> running sparse on it?

The only change in my diff is not to buildrequire sparse when not using it.
The reasons to conditionalize are unrelated to this change.  (They are some
arch problems in sparse, and sparse not in repos for buildrequire in fc<7,
in case this spec is copied for later fc[56] updates.)


Thanks,
Roland