Accept output for ! kind

I'm not entirely sure of this bang-kind stuff, but in so far as it works
at all, this test is fine.  I guess I should look at the bang-kind stuff
again, as soon as the FC branch becomes the HEAD

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail090.stderr

 
 tcfail090.hs:8:8:
-    Couldn't match kind `*' against `#'
-    When matching the kinds of `a :: *' and `ByteArray# :: #'
+    Couldn't match kind `*' against `!'
+    When matching the kinds of `a :: *' and `ByteArray# :: !'
       Expected type: ByteArray#
       Inferred type: a
     In the expression: undefined