sem_util.adb (New_Copy_Tree): Put back the declarations of the hash tables at library level.
2017-04-25 Eric Botcazou <ebotcazou@adacore.com>
* sem_util.adb (New_Copy_Tree): Put back the declarations of the
hash tables at library level. Reinstate the NCT_Hash_Tables_Used
variable and set it to True whenever the main hash table is
populated. Short- circuit the Assoc function if it is false
and add associated guards.