optimized build broken

[Tom Rodriguez]

I don't know how long this has been the case but g1CollectedHeap.hpp breaks the optimized build because the declaration of is_in_closed_subset is NOT_PRODUCT but the definition is DEBUG only and is_in_closed_subset is a virtual.  Is this a known issue?  By the way, it seems broken for a product virtual method to have non-product overrides.  Shouldn't it be defined in product too?

tom