fix for PR 4447: is this really correct?

[Joe Buck]

Kriang writes:
> I have checked the ABI specifications 
> (http://www.codesourcery.com/cxx-abi/abi.html)
> before starting on this patch.  And this bloat mangling behavior is what 
> the ABI intended.

OK.  Mark had approved applying this patch to the 3_0_release branch,
so I guess it is the thing to do.  I don't understand why the ABI is
written this way, though.  It seems odd, and since the expression must
be constant, I don't see why it was thought better to leave it unevaluated.

But, are you confident that all operators are now covered, or is it
possible that there's another ICE lurking out there if a user tries a
complicated expression?

Joe