swift234

Eagerly validate decls that conform to special protocols.

Also, validate known bridging functions if their associated modules have been
loaded.

The special protocols case is important when an imported type is literal-
convertible -- the type-checker may not think to try it otherwise. The
bridging functions (e.g. convertStringtoNSString) are important for SILGen,
which expects them to have proper types if they are present at all.

Swift SVN r8650