patch 9.1.0689: [security]: buffer-overflow in do_search() with 'rightleft'

Problem:  buffer-overflow in do_search() with 'rightleft'
          (SuyueGuo)
Solution: after reversing the text (which allocates a new buffer),
          re-calculate the text length

Github Advisory:
https://github.com/vim/vim/security/advisories/GHSA-v2x2-cjcg-f9jm

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    689,
 /**/
     688,
 /**/