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/spellfile.c

@@ -1595,6 +1595,9 @@ spell_read_tree(
     len = get4c(fd);
     if (len < 0)
 	return SP_TRUNCERROR;
+    if (len >= 0x3ffffff)
+	/* Invalid length, multiply with sizeof(int) would overflow. */
+	return SP_FORMERROR;
     if (len > 0)
     {
 	/* Allocate the byte array. */

src/version.c

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