CLang built with mingw-w64 for Windows reports "posix" as threading model

I think it is unrelated to the build system. Maybe this from
lib/Driver/Driver.cpp:

void Driver::PrintVersion(const Compilation &C, llvm::raw_ostream &OS) const {
[snip]
// Print the threading model.
//
// FIXME: Implement correctly.
OS << "Thread model: " << "posix" << '\n';
}

Ah, so it's purely a visual problem. I'll report a bug about this soon.

Thanks,

Ruben