[PATCH v2][gold] Implement --build-id=uuid on MinGW/MSYS2.

[Cary Coutant]

> gold/ChangeLog
>
>         * layout.cc: Changes for MinGW32:
>         Include windows.h and rpcdce.h.
>         (Layout::create_build_id): Generate uuid using UuidCreate().

Committed. Thanks!

-cary