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

[Carlo Cabrera via cfe-commits]

carlocab wrote:

> I didn't even realize people are using config files with clang-cl (since IIRC it doesn't support the config file command-line options).

You don't need to use config files with `clang-cl` to need this patch -- you need it if you use triple-based config files and also use `clang-cl`. The issue is that if you have, for example, a `x86_64-unknown-linux-gnu.cfg` in a location that `clang` loads by default, then this breaks `clang-cl` because running `clang-cl` also loads `x86_64-unknown-linux-gnu.cfg` (which will generically contain incompatible flags).

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