pythonPackages.wxPython: fixup build

I'm not sure why/when it started failing, but adding pkgconfig
shouldn't hurt anything.  I see no indication that
pythonPackages.pkgconfig was meant.

pkgs/development/python-modules/wxPython/3.0.nix

@@ -33,7 +33,8 @@ buildPythonPackage rec {
 
   hardeningDisable = [ "format" ];
 
-  propagatedBuildInputs = [ pkgconfig ]
+  nativeBuildInputs = [ pkgconfig ];
+  propagatedBuildInputs = [ ]
     ++ (lib.optional openglSupport pyopengl)
     ++ (lib.optionals (!stdenv.isDarwin) [ wxGTK (wxGTK.gtk) libX11 ])
     ++ (lib.optionals stdenv.isDarwin [ wxmac darwin.apple_sdk.frameworks.Cocoa ])
@@ -60,8 +61,6 @@ buildPythonPackage rec {
       ]}'
   '';
 
-  NIX_LDFLAGS = lib.optionalString (!stdenv.isDarwin) "-lX11 -lgdk-x11-2.0";
-
   buildPhase = "";
 
   installPhase = ''

pkgs/top-level/python-packages.nix

@@ -4228,6 +4228,7 @@ in {
 
   wxPython30 = callPackage ../development/python-modules/wxPython/3.0.nix {
     wxGTK = pkgs.wxGTK30;
+    inherit (pkgs) pkgconfig;
   };
 
   xml2rfc = callPackage ../development/python-modules/xml2rfc { };