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)

src/edit.c

@@ -1247,9 +1247,9 @@ doESCkey:
 	    did_cursorhold = TRUE;
 	    break;
 
-#ifdef FEAT_GUI_W32
-	    /* On Win32 ignore <M-F4>, we get it when closing the window was
-	     * cancelled. */
+#ifdef FEAT_GUI_MSWIN
+	    /* On MS-Windows ignore <M-F4>, we get it when closing the window
+	     * was cancelled. */
 	case K_F4:
 	    if (mod_mask != MOD_MASK_ALT)
 		goto normalchar;