os::win32::exit_process_or_thread should be marked noreturn

On Windows we have a non-trivial function (exit_process_or_thread) that provides the implementation of various functions like os::die, os::abort, &etc. Those os functions are marked as noreturn, so this implementation helper should also be noreturn.

Current Visual Studio versions don't seem to care (or maybe we haven't enabled the appropriate warning), but using gcc to compile for Windows (JDK-8288293) warns about the os functions returning even though declared noreturn, because exit_process_or_thread is not declared noreturn.