Dead Code: wangle::PriorityThreadFactory
Dead Code: wangle::PriorityThreadFactory

Summary: [Wangle] Dead Code: `wangle::PriorityThreadFactory`, which is but an alias to `folly::PriorityThreadFactory`.

Reviewed By: jsedgwick

Differential Revision: D6119959

fbshipit-source-id: f97cc4e85c6be8f5ba706a914687fc32203fa5bc

facebook/wangle,facebook/wangle,facebook/wangle