BUG/MINOR: anon: memory illegal accesses in tools.c with hash_anon and hash_ipanon

chipitsine reported in github issue #1872 that in function hash_anon and
hash_ipanon, index_hash can be equal to NB_L_HASH_WORD and can reach an
inexisting line table, the table is initialized hash_word[NB_L_HASH_WORD][20];
so hash_word[NB_L_HASH_WORD] doesn't exist.

No backport needed, except if anonymization mechanism is backported.
diff --git a/src/tools.c b/src/tools.c
index 474b7df..f697eac 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -5858,7 +5858,7 @@
 const char *hash_anon(uint32_t scramble, const char *string2hash, const char *prefix, const char *suffix)
 {
 	index_hash++;
-	if (index_hash > NB_L_HASH_WORD)
+	if (index_hash == NB_L_HASH_WORD)
 		index_hash = 0;
 
 	/* don't hash empty strings */
@@ -5885,7 +5885,7 @@
 	int port;
 
 	index_hash++;
-        if (index_hash > NB_L_HASH_WORD) {
+        if (index_hash == NB_L_HASH_WORD) {
                 index_hash = 0;
 	}