swift

5da4e2df - Sema: Allow unavailable decls to witness requirements in more conformances.

Sema: Allow unavailable decls to witness requirements in more conformances. In https://github.com/apple/swift/pull/63898 conformance requirement typechecking was relaxed to allow unavailable decls to witness conformance requirements as long as the conforming nominal was also unavailable. However, only nominals that were directly marked unavailable were accepted. Nominals that are declared in unavailable scopes should also be allowed to have unavailable wintesses. Resolves rdar://107052715