message: cmake: fix Ninja warning
  about BYPRODUCTS bin/opencv-340.jar
diff: @@ -21,7 +21,9 @@ set(depends ${the_module}_jar_source_copy "${OPENCV_DEPHELPER}/${the_module}_jar
  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/build.xml.in" "${OPENCV_JAVA_DIR}/build.xml" @ONLY)
  list(APPEND depends "${OPENCV_JAVA_DIR}/build.xml")
  +ocv_cmake_byproducts(__byproducts BYPRODUCTS "${OPENCV_JAR_FILE}")
  add_custom_command(OUTPUT "${OPENCV_DEPHELPER}/${the_module}_jar"
  + ${__byproducts} # required for add_custom_target() by ninja
  COMMAND ${ANT_EXECUTABLE} -noinput -k jar
  COMMAND ${CMAKE_COMMAND} -E touch "${OPENCV_DEPHELPER}/${the_module}_jar"
  WORKING_DIRECTORY "${OPENCV_JAVA_DIR}"
  