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

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> I'm getting irritated by the continuous and inconsistent reparsing of the target names in different contexts. BoundArch should be parsed once and replaced with something that isn't a string

I'm guessing this is because -march and -mcpu are used inconsistently? I'm hesitant to add such a large refactor when it's not strictly necessary for the information required.

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