[clang] clang: Add BoundArch argument to addClangTargetOptions (PR #196504)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> That's a small part of the problem. The more annoying part is figuring out the exact target is not just a matter of parsing -march/-mcpu. Some places use the raw target ID, some places want the target ID suffix split off and the base GPU name. Things are worse when you account for the explicit -m options that should change the target

Not sure if the bound architecture helps too much there, since it's not set in all cases anyway. Could we make a helper for this?

https://github.com/llvm/llvm-project/pull/196504