Commands:
git subtree add --prefix third_party/marl https://github.com/google/marl d3b8558ce8d2cf2cad1009a99aa3ff453b048639 --squash

To update:
git subtree pull --prefix third_party/SPIRV-Tools https://github.com/KhronosGroup/SPIRV-Tools <sha> --squash

Bug: b/140546382
Change-Id: If3471eb3897b128613c874a9260e0ac390d27cf1