patch applied (testsuite): Use -XGADTs rather than -X=GADTs

[Ian Lynagh]

Sat Aug  4 14:14:42 PDT 2007  Ian Lynagh <igloo at earth.li>
  * Use -XGADTs rather than -X=GADTs

    M ./tests/ghc-regress/gadt/Gadt23_AST.hs -1 +1
    M ./tests/ghc-regress/gadt/gadt23.hs -1 +1