Fix pool_init_process_context(). It forgot to set process id (not UNIX pid).
Fix pool_init_process_context(). It forgot to set process id (not UNIX
pid).

treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres