message: Add shaderc to DEPS to roll in script
  Also adds in forwarding commandline args.
diff: repo_path=$(dirname "$0")/..
  glslang_dir="third_party/glslang/"
  +shaderc_dir="third_party/shaderc/"
  spirv_cross_dir="third_party/spirv-cross/"
  spirv_headers_dir="third_party/spirv-headers/"
  spirv_tools_dir="third_party/SPIRV-Tools/"
  cd "$repo_path"
  -roll-dep "${glslang_dir}" "${spirv_cross_dir}" "${spirv_headers_dir}" "${spirv_tools_dir}"
  +roll-dep "$@" "${glslang_dir}" "${shaderc_dir}" "${spirv_cross_dir}" "${spirv_headers_dir}" "${spirv_tools_dir}"
  