nixpkgs: remove redundant attribute sip

Because:

 1. It is a mere alias of `pythonPackages.sip`
 2. It is usually not needed since propagated by `pyqt4`
 3. It makes it easy to have a packages depend on two different versions
 of sip

pkgs/desktops/kde-4.14/applications/kate.nix

@@ -1,8 +1,8 @@
-{ stdenv, kde, kdelibs, kactivities, qjson, pyqt4, sip, python, pykde4}:
+{ stdenv, kde, kdelibs, kactivities, qjson, pyqt4, python, pykde4}:
 
 kde {
 
-  buildInputs = [ kdelibs kactivities qjson pyqt4 sip python pykde4 ];
+  buildInputs = [ kdelibs kactivities qjson pyqt4 python pykde4 ];
 
   meta = {
     description = "Kate, the KDE Advanced Text Editor, as well as KWrite";

pkgs/desktops/kde-4.14/kdebindings/pykde4.nix

@@ -1,4 +1,4 @@
-{ kde, kdelibs, python, sip, pyqt4, kdepimlibs, shared_desktop_ontologies,
+{ kde, kdelibs, python, pyqt4, kdepimlibs, shared_desktop_ontologies,
   polkit_qt4, boost, lndir, pkgconfig }:
 
 let pydir = "lib/python${python.majorVersion}"; in
@@ -14,7 +14,7 @@ kde {
 
   nativeBuildInputs = [ pkgconfig ];
 
-  propagatedBuildInputs = [ pyqt4 sip ];
+  propagatedBuildInputs = [ pyqt4 ];
 
   preConfigure =
     ''