patch 8.0.0697: recorded key sequences may become invalid

Problem:    Recorded key sequences may become invalid.
Solution:   Add back KE_SNIFF removed in 7.4.1433. Use fixed numbers for the
            key_extra enum.

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    697,
 /**/
     696,
 /**/