swift234

Start detangling the uses of TypeDecl::getProtocols(). NFC

Getting the protocols of an arbitrary type doesn't make sense, so start phasing this out by introducing specialized entry points that do make sense:
  - get the inherited protocols of a ProtocolDecl
  - get the conforming protocols for an associated type or generic
  type parameter
  - (already present) ask for the protocols to which a nominal type conforms

Swift SVN r26411