BUG: Fix ITKDoxygenXML by copying instead of renaming directory

Resolves build issue on Windows where directory populated with
ITKDoxygenXML archive contents could not be directly renamed, but could
be copied and then deleted as a one-time build operation.

Author: tbirdso

CMake/ITKDoxygenXML.cmake

@@ -5,7 +5,7 @@ set( ITKDoxygenXML_TEMP_DIR ${CMAKE_BINARY_DIR}/ITKDoxygenXML-TEMP )
 add_custom_command( OUTPUT ${ITKDoxygenXML_DIR}/index.xml
   COMMAND ${CMAKE_COMMAND} -DITKDoxygenXML_TEMP_DIR="${ITKDoxygenXML_TEMP_DIR}" -P ${ITKSphinxExamples_SOURCE_DIR}/CMake/DownloadDoxygenXML.cmake
   COMMAND ${CMAKE_COMMAND} -E chdir "${ITKDoxygenXML_TEMP_DIR}" ${CMAKE_COMMAND} -E tar xzf "${ITKDoxygenXML_TEMP_DIR}/itk-doxygen-xml.tar.gz"
-  COMMAND ${CMAKE_COMMAND} -E rename "${ITKDoxygenXML_TEMP_DIR}/xml" "${ITKDoxygenXML_DIR}"
+  COMMAND ${CMAKE_COMMAND} -E copy_directory "${ITKDoxygenXML_TEMP_DIR}/xml" "${ITKDoxygenXML_DIR}"
   COMMAND ${CMAKE_COMMAND} -E remove_directory "${ITKDoxygenXML_TEMP_DIR}"
   COMMENT "Downloading and unpacking the Doxygen XML"
   )