Exclude >= 2.8.3 from reimplementation of CMAKE_CURRENT_LIST_DIR

This avoids violation of possible future CMake policy checks
regarding reserved/read-only variables.

cmake/templates/OpenCVConfig.cmake.in

@@ -47,9 +47,11 @@ endif()
 
 if(NOT TARGET opencv_core)
   # Extract directory name from full path of the file currently being processed.
-  # Note that CMake 2.8.3 introduced CMAKE_CURRENT_LIST_DIR, but we do this
-  # manually to support older versions of CMake as well.
-  get_filename_component(CMAKE_CURRENT_LIST_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
+  # Note that CMake 2.8.3 introduced CMAKE_CURRENT_LIST_DIR. We reimplement it
+  # for older versions of CMake to support these as well.
+  if(CMAKE_VERSION VERSION_LESS "2.8.3")
+    get_filename_component(CMAKE_CURRENT_LIST_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
+  endif()
 
   include(${CMAKE_CURRENT_LIST_DIR}/OpenCVModules${OpenCV_MODULES_SUFFIX}.cmake)
 endif()