inc: winapi: Allow win/ole2.bi to be included alone/directly again

This is done by the disphelper headers.

(cherry picked from commit dd4fc94)

Author: dkl

changelog.txt

@@ -10,7 +10,7 @@ Version 1.02.1
 [fixed]
 - 1.02.0 regression: win/winuser.bi: Renamed INPUT typedef to INPUT_ to avoid conflicts with the quirk keyword (due to bug #730)
 - 1.02.0 regression: OpenGL binding: glGetString() and some others use ZString Ptr instead of GLubyte Ptr again
-- 1.02.0 regression: Windows API binding: REFIID and some other REF* types were missing; wsprintf/wvsprintf declarations were missing
+- 1.02.0 regression: Windows API binding: REFIID and some other REF* types were missing; wsprintf/wvsprintf declarations were missing; ole2.bi couldn't be included directly/alone anymore.
 - bindings: Various previously untranslated (or wrongly translated) #defines in SDL2, X11, crt/pthread, Windows API
 - Windows API binding: DirectX headers missed some declarations and some didn't compile
 - crt/string.bi, crt/mem.bi: Added CONSTs to function declarations

inc/win/winerror.bi

@@ -2,6 +2,8 @@
 
 #pragma once
 
+#include once "_mingw.bi"
+
 #define _WINERROR_
 const FACILITY_WINDOWSUPDATE = 36
 const FACILITY_WINDOWS_CE = 24