patch 8.1.0856: when scrolling a window the cursorline is not always updated

Problem:    When scrolling a window other than the current one the cursorline
            highlighting is not always updated. (Jason Franklin)
Solution:   Call redraw_for_cursorline() after scrolling.  Only set
            w_last_cursorline when drawing the cursor line.  Reset the lines
            to be redrawn also when redrawing the whole window.
diff --git a/src/normal.c b/src/normal.c
index b953b7d..b512b55 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -4587,6 +4587,10 @@
 	}
     }
 # endif
+# ifdef FEAT_SYN_HL
+    if (curwin != old_curwin && curwin->w_p_cul)
+	redraw_for_cursorline(curwin);
+# endif
 
     curwin->w_redr_status = TRUE;