Hack to fix llvm/clang build on Darwin

(Or at least restore it to the same level as brokenness as before the
staging merge. I.e. it depends on gcc-apple, which doesn't build on
standard 10.9 systems.)

pkgs/development/compilers/gcc/4.2-apple64/default.nix

@@ -45,5 +45,5 @@ stdenv.mkDerivation rec {
 
   buildInputs = stdenv.lib.optionals langF77 [ gmp mpfr bison flex ];
 
-  meta.broken = true;
+  #meta.broken = true;
 }