RULES pragma broken in the head

[rl]

This module:

module Foo where
{-# RULES "id" forall x. id x = x #-}

compiles fine with 6.8.3 but the HEAD says (twice):

Foo.hs:2:0: Unrecognised pragma

Adding -frewrite-rules has no effect. But with -XRank2Types, it compiles fine for some reason.

[igloo]

#2497 and #2500 now cover these points.