RFR: JDK-8211792: Fix misplaced BarrierSet forward declarations

[Aleksey Shipilev]

On 10/05/2018 11:46 PM, Roman Kennke wrote:
> In templateTable.hpp there's a forward declaration for BarrierSet
> missing, while in oop.hpp we have a gratituous one.
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8211792
> Webrev:
> http://cr.openjdk.java.net/~rkennke/JDK-8211792/webrev.00/

Looks good to me.

Indeed, templateTable.hpp needs the declaration for:
    97   static BarrierSet*     _bs;                    // Cache the barrier set.

...and oop.hpp does not reference BarrierSet anywhere. The transitive dependencies that get
BarrierSet from oop.hpp should really get BarrierSet explicitly. I have build Linux x86_64/fastdebug
without PCH to make sure this does not happen now on common paths.

Thanks,
-Aleksey