Change to std::move inside Worker.h
Change to std::move inside Worker.h

Summary: For the current implementations it's fine we don't std::move here. However an implementation that requires we don't copy/destroy will fail. This fixes it.

Reviewed By: lstyls

Differential Revision: D4267174

fbshipit-source-id: d4fc272d09931e8c79071e6bc22899d6ad13755b

yqzhang/treadmill,yqzhang/treadmill