patch 8.0.0686: extra redraw when using CTRL-L in second window

Problem:    When typing CTRL-L in a window that's not the first one, another
            redraw will happen later. (Christian Brabandt)
Solution:   Reset must_redraw after calling screenclear().
diff --git a/src/version.c b/src/version.c
index d595256..e659f8c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    686,
+/**/
     685,
 /**/
     684,