simpleitk: itk -> itk4

- simpleitk 1.2.4 is incompatible with ITK 5.1, so this can be reverted when 2.x is released.

pkgs/development/libraries/simpleitk/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchFromGitHub, cmake, git, swig, lua, itk, tcl, tk }:
+{ stdenv, fetchFromGitHub, cmake, git, swig, lua, itk4, tcl, tk }:
 
 stdenv.mkDerivation rec {
   pname = "simpleitk";
@@ -12,7 +12,7 @@ stdenv.mkDerivation rec {
   };
 
   nativeBuildInputs = [ cmake git swig ];
-  buildInputs = [ lua itk ];
+  buildInputs = [ lua itk4 ];
 
   cmakeFlags = [ "-DBUILD_SHARED_LIBS=ON" "-DCMAKE_CXX_FLAGS='-Wno-attributes'" ];