tree_data OPTIMIZE optimize creation of children htable

Here, we know the number of children that will be added in the hash
table, so create the hash table with the correct number of elements to
avoid automatic resizes.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>

src/tree_data_hash.c

@@ -182,8 +182,7 @@ lyd_insert_hash(struct lyd_node *node)
             }
         }
         if (u >= LYD_HT_MIN_ITEMS) {
-            /* create hash table, insert all the children */
-            node->parent->children_ht = lyht_new(1, sizeof(struct lyd_node *), lyd_hash_table_val_equal, NULL, 1);
+            node->parent->children_ht = lyht_new(lyht_get_fixed_size(u), sizeof(struct lyd_node *), lyd_hash_table_val_equal, NULL, 1);
             LY_LIST_FOR(node->parent->child, iter) {
                 if (iter->schema) {
                     LY_CHECK_RET(lyd_insert_hash_add(node->parent->children_ht, iter, 1));