al_destroy_thread - Allegro 5 API

       Free  the  resources  used  by a thread.  Implicitly performs al_join_thread(3alleg5) on the thread if it
       hasn’t been done already.

       Does nothing if thread is NULL.

       al_destroy_thread - Allegro 5 API

al_join_thread(3alleg5).

Allegro reference manual                                                              al_destroy_thread(3alleg5)

              #include <allegro5/allegro.h>

              void al_destroy_thread(ALLEGRO_THREAD *thread)