Added a new function for dynamorio's hashtable implementation.
The function allows the calling of a function for each payload entered in the hashtable. It is useful if updates need to be performed for all payloads.
Abstracting this functionality from the implementation of the hashtable would typically require managing an external data-structure, such as a list, that contains the payloads or the keys (where payloads are then retrieved via look-up operations). The proposed approach avoids this.