message: Remove duplicate data folders for viewer
  This changelist restores an earlier improvement lost in the last merge, removing duplicate library and resource folders that were generated during the MaterialXView build process.
diff: @@ -55,13 +55,6 @@ target_include_directories(
  ${CMAKE_CURRENT_SOURCE_DIR}/NanoGUI/include
  ${NANOGUI_EXTRA_INCS})
  -add_custom_command(TARGET MaterialXView POST_BUILD
  - COMMAND ${CMAKE_COMMAND} -E copy_directory
  - ${CMAKE_CURRENT_SOURCE_DIR}/../../libraries ${CMAKE_CURRENT_BINARY_DIR}/libraries)
  -add_custom_command(TARGET MaterialXView POST_BUILD
  - COMMAND ${CMAKE_COMMAND} -E copy_directory
  - ${CMAKE_CURRENT_SOURCE_DIR}/../../resources ${CMAKE_CURRENT_BINARY_DIR}/resources)
  -
  if(MATERIALX_BUILD_OIIO AND OPENIMAGEIO_ROOT_DIR)
  add_custom_command(TARGET MaterialXView POST_BUILD
  COMMAND ${CMAKE_COMMAND} -E copy_directory
  