patch 9.0.0664: bad redrawing with spell checking, using "C" and "$" in 'cpo'

Problem:    Bad redrawing with spell checking, using "C" and "$" in 'cpo'.
Solution:   Do not redraw the next line when "$" is in 'cpo'. (closes #11285)
diff --git a/src/edit.c b/src/edit.c
index 2484fe5..ab268c1 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -1738,8 +1738,8 @@
 }
 
 /*
- * Called when p_dollar is set: display a '$' at the end of the changed text
- * Only works when cursor is in the line that changes.
+ * Called when "$" is in 'cpoptions': display a '$' at the end of the changed
+ * text.  Only works when cursor is in the line that changes.
  */
     void
 display_dollar(colnr_T col_arg)