- change prerequisites for generating equals/hashCode/toString in a data class:
previously they were generated if the corresponding method is trivial (i.e.
it comes from kotlin.Any), now we're generating it always unless it'll cause
a JVM signature clash error (see KT-6206)
- use static KotlinBuiltIns.isXxx methods to compare types instead of checking
against descriptors loaded from certain built-ins instance, this is quicker
and more correct in environments where several built-ins are possible
- don't use isOrOverridesSynthesized, it's not relevant for
equals/hashCode/toString because functions with these names are never
synthesized
#KT-6206 Fixed
