Please tag happy-1.18.4-4.fc12 for f12.

This change just drops the %post scriptlet
(needed previously to set selinux fcontext for ghc runtime).

The current build in rawhide gives a %post error
preventing happy and haskell-platform from installing correctly:

"happy post script failed"
https://bugzilla.redhat.com/show_bug.cgi?id=526664

http://koji.fedoraproject.org/koji/buildinfo?buildID=134662
I tested the new package installs and works correctly under enforcing in f12.

This is a small change with little risk - should be good for F12-beta too.