swift234

Sema: Finish staging back in availability checking in synthesized functions

Remove the suppression of deprecation and potential unavailability diagnostics in
synthesized functions. We still suppress some explicit unavailability diagnostics -- those
in synthesized functions in synthesized functions that are lexically contained in
declarations that are themselves annotated as unavailable. For these cases, the right
solution <rdar://problem/20491640> is to not synthesize the bodies of these functions in
the first place.

rdar://problem/20024980

Swift SVN r27203