patch 8.1.0941: macros for MS-Windows are inconsistent

Problem:    Macros for MS-Windows are inconsistent, using "32", "3264 and
            others.
Solution:   Use MSWIN for all MS-Windows builds.  Use FEAT_GUI_MSWIN for the
            GUI build. (Hirohito Higashi, closes #3932)
diff --git a/src/if_ole.cpp b/src/if_ole.cpp
index 0888883..8ee348d 100644
--- a/src/if_ole.cpp
+++ b/src/if_ole.cpp
@@ -6,7 +6,7 @@
  * Do ":help credits" in Vim to see a list of people who contributed.
  */
 
-#if defined(FEAT_OLE) && defined(FEAT_GUI_W32)
+#if defined(FEAT_OLE) && defined(WIN32) && defined(FEAT_GUI)
 /*
  * OLE server implementation.
  *