[clang] Reland [Driver] Add support for GCC installation detection in Baremetal toolchain (PR #145390)

[Daniel Thornburgh via cfe-commits]

mysterymath wrote:

I've issued a trial run here: https://ci.chromium.org/ui/p/fuchsia/builders/toolchain.ci.shadow/clang-linux-x64/b8710885146355675473/overview

https://github.com/llvm/llvm-project/pull/145390