Merge branch 'remove-include-duplicates'

* remove-include-duplicates:
  Don't use set_directory_properties in UseCTK.cmake

CMake/UseCTK.cmake.in

@@ -28,11 +28,10 @@ if(NOT CTK_USE_FILE_INCLUDED)
   set(CTK_USE_FILE_INCLUDED 1)
 
   # Add include directories needed to use CTK.
-  get_directory_property(includes INCLUDE_DIRECTORIES)
-  list(APPEND includes ${CTK_INCLUDE_DIRS})
-  # But don't add duplicated directories (e.g. VTK or ITK)
-  list(REMOVE_DUPLICATES includes)
-  set_directory_properties(INCLUDE_DIRECTORIES ${includes})
+  get_directory_property(existing_include_directories INCLUDE_DIRECTORIES)
+  set(new_include_directories ${CTK_INCLUDE_DIRS})
+  list(REMOVE_ITEM new_include_directories ${existing_include_directories})
+  include_directories(${new_include_directories})
 
   if (NOT DEFINED QT_QMAKE_EXECUTABLE)
     set(QT_QMAKE_EXECUTABLE ${CTK_QT_QMAKE_EXECUTABLE})