patch 8.0.1449: slow redrawing with DirectX

Problem:    Slow redrawing with DirectX.
Solution:   Avoid calling gui_mch_flush() unnecessarily, especially when
            updating the cursor. (Ken Takata, closes #2560)
diff --git a/src/getchar.c b/src/getchar.c
index 18dc1a6..70cf4f1 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -2972,16 +2972,10 @@
     if (wait_time == -1L || wait_time > 100L)  /* flush output before waiting */
     {
 	cursor_on();
-	out_flush();
-#ifdef FEAT_GUI
-	if (gui.in_use)
-	{
-	    gui_update_cursor(FALSE, FALSE);
-# ifdef FEAT_MOUSESHAPE
-	    if (postponed_mouseshape)
-		update_mouseshape(-1);
-# endif
-	}
+	out_flush_cursor(FALSE, FALSE);
+#if defined(FEAT_GUI) && defined(FEAT_MOUSESHAPE)
+	if (gui.in_use && postponed_mouseshape)
+	    update_mouseshape(-1);
 #endif
     }