swift234

Sema: Fixes for conformance between higher-kind metatypes

For a concrete type A and protocol type P, A <c P now implies
A.Type <c P.Type, not just A.Type < P.Type. This in turn means
that A.Type.Type <c P.Type.Type. To make the coercion work,
recursively peel off metatype layers when collecting conformances
and in a similar situation in IRGen.

Swift SVN r29377