message: Mark crypto::tink::util::error::Code as deprecated.
  This CL is a part of the Tink migration to using absl::Status{,Or} and absl::StatusCode.
diff: @@ -33,7 +33,7 @@ namespace error {
  // These values match the error codes in the codes.proto file of the original.
  -enum Code {
  +enum ABSL_DEPRECATED("Prefer using absl::StatusCode instead.") Code {
  // Not an error; returned on success
  OK = 0,
  