patch 8.0.0322: possible overflow with corrupted spell file

Problem:    Possible overflow with spell file where the tree length is
            corrupted.
Solution:   Check for an invalid length (suggested by shqking)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    322,
 /**/
     321,
 /**/