patch 9.0.0318: clearing screen causes flicker

Problem:    Clearing screen causes flicker.
Solution:   Do not clear but redraw in more cases.  Add () to "wait_return".
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index a41e067..3db1592 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -348,7 +348,7 @@
     if (!(p_confirm || (cmdmod.cmod_flags & CMOD_CONFIRM)))
 #endif
     {
-	// There must be a wait_return for this message, do_buffer()
+	// There must be a wait_return() for this message, do_buffer()
 	// may cause a redraw.  But wait_return() is a no-op when vgetc()
 	// is busy (Quit used from window menu), then make sure we don't
 	// cause a scroll up.