python.pkgs.cython: use pkg-config instead of python.pkgs.pkgconfig

It does not need the Python interface to pkg-config.

Note I think the majority of Python packages that use pkgconfig should
actually use pkg-config.

pkgs/development/python-modules/Cython/default.nix

@@ -5,7 +5,7 @@
 , fetchpatch
 , python
 , glibcLocales
-, pkgconfig
+, pkg-config
 , gdb
 , numpy
 , ncurses
@@ -34,7 +34,7 @@ in buildPythonPackage rec {
   };
 
   nativeBuildInputs = [
-    pkgconfig
+    pkg-config
   ];
   checkInputs = [
     numpy ncurses