improve performance for table resize

Signed-off-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>
use lastfree field to improve userspace table set operation

Signed-off-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>
tiny header file cleanup

Signed-off-by: Jovi Zhangwei <jovi.zhangwei@gmail.com>