Remove unnecessary memset of AIO control block
Remove unnecessary memset of AIO control block

anirajk/RAMCloud,jblomer/ramcloud,jblomer/ramcloud,utah-scs/RAMCloud,utah-scs/RAMCloud,utah-scs/RAMCloud,SMatsushi/RAMCloud,anirajk/RAMCloud,anirajk/RAMCloud,SMatsushi/RAMCloud,anirajk/RAMCloud,jblomer/ramcloud,SMatsushi/RAMCloud,utah-scs/RAMCloud,anirajk/RAMCloud,utah-scs/RAMCloud,anirajk/RAMCloud,jblomer/ramcloud,SMatsushi/RAMCloud,utah-scs/RAMCloud,jblomer/ramcloud,SMatsushi/RAMCloud,jblomer/ramcloud,SMatsushi/RAMCloud