Revert "cairo: fix build inputs"

This reverts commit e557a432e07441a508544fca2aba3be6fd9860c0.

Sorry about this. Accidentally got into my git push. Did not mean to
cause a mass rebuild!

pkgs/development/libraries/cairo/default.nix

···
 
   nativeBuildInputs = [
     pkgconfig
-  ];
-
-  buildInputs = [
     libiconv
     libintl
   ] ++ optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [