* stdenv.mkDerivation: add any attributes in the "passthru" attribute

set to the result, but don't use them in the actual derivation (so
  they're not inputs).  Useful to pass through extra attributes that
  are not inputs, but should be made available to Nix expressions
  using the derivation (e.g., in assertions).

svn path=/nixpkgs/trunk/; revision=6521

pkgs/development/libraries/qt-3/default.nix

@@ -57,4 +57,6 @@ stdenv.mkDerivation {
     # randr.h and Xrandr.h need not be in the same prefix.
     ./xrandr.patch
   ];
+
+  passthru = {inherit mysqlSupport;};
 }