Suppress the dummy target comment appearing in build log on each build.

Source/ThirdParty/rapidjson/CMakeLists.txt

@@ -24,7 +24,7 @@
 set (TARGET_NAME rapidjson)
 
 # Setup target
-add_custom_target(${TARGET_NAME} ALL COMMENT "Dummy target just so that its post-build step can install headers to the build tree")
+add_custom_target(${TARGET_NAME} ALL)   # Dummy target just so that its post-build step can install headers to the build tree
 
 # Install headers for building the Urho3D library
 install_header_files (DIRECTORY include/rapidjson/ DESTINATION ${DEST_INCLUDE_DIR}/ThirdParty/rapidjson FILES_MATCHING PATTERN *.h BUILD_TREE_ONLY)  # Note: the trailing slash is significant