add missing memset in data structure initialization

src/api/init_msg.c

@@ -113,6 +113,7 @@ void slurm_init_job_desc_msg(job_desc_msg_t * job_desc_msg)
  */
 void slurm_init_part_desc_msg (update_part_msg_t * update_part_msg)
 {
+	memset(update_part_msg, 0, sizeof(update_part_msg_t));
 	update_part_msg->default_part 	= (uint16_t) NO_VAL;
 	update_part_msg->default_time   = (uint32_t) NO_VAL;
 	update_part_msg->hidden 	= (uint16_t) NO_VAL;