Making enum class-related tests unmuted requires implementing
a special "compatibility" mode for IR tree dumper to filter out
fake override declarations leaking from java.enum.Enum and
kotlin.Enum (JVM-only) classes.
This doesn't reduce the quality of tests, because the flags are still
printed for declarations themselves. We only omit them in references.
However, this makes the tests more compatible with non-JVM backends
(see KT-58605), because flags of referenced stdlib declarations may
differ among target platforms.
Pavel Kunyavskiy