[clang] [clang-scan-deps] Infer the target from the executable name (PR #108189)

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

Thanks! How do you feel about potentially backporting this to 19.x after a while? It’s not an urgent fix for a regression or something like that, but it’s kinda trivial enough. (In any case, it’d be after the first 19.1.0 is cut.)

https://github.com/llvm/llvm-project/pull/108189