patch applied (ghc-6.6/testsuite): MERGED: Add a test gadt23 from Christophe Poucet

[Ian Lynagh]

Sun Mar 11 14:21:45 PDT 2007  Ian Lynagh <igloo at earth.li>
  * MERGED: Add a test gadt23 from Christophe Poucet
  Ian Lynagh <igloo at earth.li>**20070311195336

    A ./tests/ghc-regress/gadt/Gadt23_AST.hs
    M ./tests/ghc-regress/gadt/Makefile +7
    M ./tests/ghc-regress/gadt/all.T +3
    A ./tests/ghc-regress/gadt/gadt23.hs