kdeFrameworks: fixup inputs and outputs

- Reduce environment pollution with a separate $bin output containing programs,
  plugins, and shared data. Libraries remain in $out and are not installed into
  the environment.
- Only propagate build inputs as required.

pkgs/development/libraries/kde-frameworks/kwindowsystem/default.nix

@@ -10,10 +10,11 @@ mkDerivation {
     maintainers = [ lib.maintainers.ttuegel ];
     broken = builtins.compareVersions qtbase.version "5.6.0" < 0;
   };
-  nativeBuildInputs = [ extra-cmake-modules qttools ];
-  propagatedBuildInputs = [ qtx11extras ];
+  nativeBuildInputs = [ extra-cmake-modules ];
+  buildInputs = [ qttools qtx11extras ];
+  propagatedBuildInputs = [ qtbase ];
   patches = copyPathsToStore (lib.readPathsFromFile ./. ./series);
   preConfigure = ''
-    NIX_CFLAGS_COMPILE+=" -DNIXPKGS_QT_PLUGIN_PATH=\"$out/$qtPluginPrefix\""
+    NIX_CFLAGS_COMPILE+=" -DNIXPKGS_QT_PLUGIN_PATH=\"''${!outputBin}/$qtPluginPrefix\""
   '';
 }