def include_args(aux_libraries)
      all_aux_include_dirs = arduino_library_src_dirs(aux_libraries)
      places = [ARDUINO_HEADER_DIR, UNITTEST_HEADER_DIR] + header_dirs + all_aux_include_dirs
      places.map { |d| "-I#{d}" }
    end
def include_args(aux_libraries)
      all_aux_include_dirs = arduino_library_src_dirs(aux_libraries)
      places = [ARDUINO_HEADER_DIR, UNITTEST_HEADER_DIR] + header_dirs + all_aux_include_dirs
      places.map { |d| "-I#{d}" }
    end
GCC command line arguments for including aux libraries
 @param aux_libraries [Array<Pathname>] The external Arduino libraries required by this project
 @return [Array<String>] The GCC command-line flags necessary to include those libraries