Removed a last flaw and use `cvs export' instead of `cvs checkout' now.

The first version of a script that allows building rpm packages directly from
CVS.  It currently works for ghc only, but will be extended to cover the
other fptools.

It should work on all rpm-based systems, as I tried to avoid any dependency on
Red Hat systems (as far as I am aware of them).  In particular, the rpm build
process is carried out below /tmp instead of the standard /usr/src/redhat
hierarchy.

By default the cvs head of the anonymous repository is built, but cvs-style -d
-D, and -r options allow to built from a different repository and revision.

[This version is only half tested, because the CVS head seems to not build
anymore today.]