[R6RS] `eqv?' on immutable records

[Anton van Straaten]

Michael Sperber wrote:
>>E.g. what would the impact on the formal semantics be?
> 
> 
> Well, location tags are needed for mutable objects anyway.  I'm not sure
> if it's grown the "immutable" flag I asked for a long time ago, but I'll
> check tomorrow.  In either case, it shouldn't be a problem.

OK.  Another devil's advocate concern is backwards compatibility.  Is 
the idea to allow location tagging of immutable values, but not require it?