[clang] [clang][Driver] Support passing arbitrary args to -cc1as with -Xclangas. (PR #100714)

[Alex Rønne Petersen via cfe-commits]

alexrp wrote:

I'm assuming this failure is not caused by my changes: https://github.com/llvm/llvm-project/actions/runs/10107700664/job/27952082137?pr=100714

https://github.com/llvm/llvm-project/pull/100714