patch 9.1.1136: Match highlighting marks a buffer region as changed

Problem:  Match highlighting marks a buffer region to be redrawn as if
          its buffer text was changed, unnecessarily invoking syntax code.
Solution: Set the `w_redraw_top/bot` variables instead of the b_mod_* ones
          (Luuk van Baal)

closes: #16697

Signed-off-by: Luuk van Baal <luukvbaal@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/fold.c b/src/fold.c
index 64f9447..b165dc9 100644
--- a/src/fold.c
+++ b/src/fold.c
@@ -2384,12 +2384,7 @@
     // this in other situations, the changed lines will be redrawn anyway and
     // this method can cause the whole window to be updated.
     if (end != bot)
-    {
-	if (wp->w_redraw_top == 0 || wp->w_redraw_top > top)
-	    wp->w_redraw_top = top;
-	if (wp->w_redraw_bot < end)
-	    wp->w_redraw_bot = end;
-    }
+	redraw_win_range_later(wp, top, end);
 
     invalid_top = (linenr_T)0;
 }