Lack of "start" member function declare in WBThrottle.h

Signed-off-by: Haomai Wang <haomaiwang@gmail.com>
Merge pull request #1002 from yuyuyu101/wip-7062

Lack of "start" member function declare in WBThrottle.h
make check runs ok

Reviewed-by: Loic Dachary <loic@dachary.org>