Consider using git submodules for third party dependencies?

Rather than the tedious process of cloning third party dependencies manually, making sure that the versions are compatible, I would recommend using git submodules.

By doing this:

cd third_party
git submodule add https://github.com/google/googletest.git
git submodule add https://github.com/google/glslang.git
git submodule add https://github.com/KhronosGroup/SPIRV-Tools.git spirv-tools
git submodule add https://github.com/KhronosGroup/SPIRV-Headers.git spirv-headers
then commit and push, you would simplify the process for everyone compiling shaderc, and everyone including shaderc as a submodule to their git repository, as the source and all dependencies could be fetched with one command:

git clone --recurse-submodules https://github.com/google/shaderc.git