[clang] [clang][Driver] Fix triple config loading for clang-cl (PR #111397)

[Hans Wennborg via cfe-commits]

zmodem wrote:

Looks like I was wrong. clang-cl does support `--config` since daebf2c13ce27ac6a7403525cc7fcbc063eb892e, so I suppose we can't just ignore these files.

Your change to update the triple based on clang-cl mode earlier makes sense to me.

I'm less sure about manually inspecting the `/arm64EC` flag in that code. `Driver::loadDefaultConfigFiles()` has logic to figure out the triple, is it not handled there?

I'm even less sure about the "The config file may have changed the architecture so apply it" part. It's not clear to me that we need it at all, and if we do need it, why is it specific to the `/arm64EC` flag?

https://github.com/llvm/llvm-project/pull/111397