[llvm] [Support] Resolve symlinks in `getMainExecutable()` on Windows (PR #76304)

[Alexandre Ganea via llvm-commits]

aganea wrote:

@glandium It is a bit unfortunate but it seems the previous behavior was "by chance". Do you happen to know what happens on Linux under the same conditions? (path with spaces) I could send a PR to add `sys::printArg()` where needed, if that sounds good to you?

https://github.com/llvm/llvm-project/pull/76304