RFR 8204850: BarrierSet::make_* should be static

[Thomas Schatzl]

Hi,

On Tue, 2018-06-12 at 14:17 +0200, Aleksey Shipilev wrote:
> Thanks! Also is it trivial? I had it through jdk-submit as part of
> Epsilon change, and it seems
> fine. I am pushing it shortly.

  I think this could qualify as trival change.

Thanks,
  Thomas