RFR: Let AccessBarrier call directly to inlineable resolve_forwarded

[Roman Kennke]

Am 05.07.2018 um 13:20 schrieb Aleksey Shipilev:
> On 07/05/2018 01:00 PM, Roman Kennke wrote:
>> This is a small cleanup in SBS to call directly to inlineable
>> SBS::resolve_forwarded().
> 
> Okay, good!

I needed to back-out this change because it breaks full-gc.
read_barrier() specially protects this by checking has_fwded_objs.

Roman