swift234

Respect access control for member lookups as well.

(when -enable-access-control is used)

Note that this is currently circumvented when looking up requirements in a
protocol. We're not currently set up to pass along the DeclContext where a
protocol's requirements are requested /from/, so we're just relying on the
fact that the requirements have the same visibility as the protocol in 1.0.

Swift SVN r19355