Summary:
Previously, the Windows build was litered with warnings of the form (typo included):

  warning C4250: 'C1': inherits 'C2::C2::method' via dominance
  note: see declaration of 'C2::method'

Microsoft doesn't offer any recommendation, and the internet suggest that the
right `using` should silence it. That's unfortunately not the case, adding:
  using C2::method
In `C1` doesn't do anything, and the compiler still complains :(.

Since the warning appears to be non-actionable, and looks more like a
"notice" than a warning, let's just silence it.

Reviewed By: wez

Differential Revision: D21395095

fbshipit-source-id: ae661b3ed61303e6361b8a15d9e7c6b9627ea8c1