[clang] [clang][scan-build] Treat --use-cc and --use-c++ as shell commands (PR #131932)

[Balázs Benics via cfe-commits]

balazs-benics-sonarsource wrote:

I'd prefer option 2, because why else would we have a default compiler if that wasn't used in some workflows.
A warning could never hurt. I'm also flexible on the subject.

https://github.com/llvm/llvm-project/pull/131932