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/ex_docmd.c b/src/ex_docmd.c
index 8cdb046..6e61cca 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -177,7 +177,7 @@
 # define ex_gui			ex_nogui
 static void	ex_nogui(exarg_T *eap);
 #endif
-#if defined(FEAT_GUI_W32) && defined(FEAT_MENU) && defined(FEAT_TEAROFF)
+#if defined(FEAT_GUI_MSWIN) && defined(FEAT_MENU) && defined(FEAT_TEAROFF)
 static void	ex_tearoff(exarg_T *eap);
 #else
 # define ex_tearoff		ex_ni
@@ -8866,7 +8866,7 @@
 }
 #endif
 
-#if defined(FEAT_GUI_W32) && defined(FEAT_MENU) && defined(FEAT_TEAROFF)
+#if defined(FEAT_GUI_MSWIN) && defined(FEAT_MENU) && defined(FEAT_TEAROFF)
     static void
 ex_tearoff(exarg_T *eap)
 {
@@ -9853,7 +9853,7 @@
     if (need_maketitle)
 	maketitle();
 #endif
-#if defined(WIN3264) && !defined(FEAT_GUI_W32)
+#if defined(MSWIN) && !defined(FEAT_GUI_MSWIN)
     resize_console_buf();
 #endif
     RedrawingDisabled = r;