Suppress "inherits via dominance" warning in IOThreadPoolExecutor.h
Suppress "inherits via dominance" warning in IOThreadPoolExecutor.h

Summary: This is the expected design of the class, so suppress the warning using `FOLLY_MSVC_DISABLE_WARNING` instead of fixing the issue.

Reviewed By: Orvid

Differential Revision: D18733718

fbshipit-source-id: ff9368a9ce31ad11e5992d65f0b5b26b2859ff02

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly