RFR: Remove safe_equals()

[Aleksey Shipilev]

On 07/06/2018 05:51 PM, Roman Kennke wrote:
> A looong while ago we introduced oopDesc::safe_equals() as a way to do
> efficient object comparison without GC barriers, but also verify that
> we're actually comparing to-space copies. It turned out that the only
> place where we ever needed it was in ReferenceProcessor, and even there
> it never triggered. Usage there can be reasoned about well enough, I
> propose to drop safe_equals() and related code to further our reduce
> upstream diff.
> 
> http://cr.openjdk.java.net/~rkennke/remove-safeeq/webrev.00/
> 
> For god-knows-what-reason, there's a missing BarrierSet fwd decl in
> templateTable.hpp that has previously been 'covered' by our added
> barrierSet.hpp inclusion in oop.hpp. No idea why upstream hasn't been
> hit by this.?
> 
> Ok to push?

Looks good.

-Aleksey