symtab: fix some leaks

* src/symlist.c (symbol_list_free): Deep free it.
* src/symtab.c (symbols_free, semantic_types_sorted): Free it too.
(symbols_do, sorted): Call by address.

src/symlist.c

@@ -119,6 +119,8 @@ symbol_list_free (symbol_list *list)
     {
       next = node->next;
       named_ref_free (node->named_ref);
+      if (node->content_type == SYMLIST_TYPE)
+        free (node->content.sem_type);
       free (node);
     }
 }