RFR: 8143014: Access PtrQueue member offsets through derived classes

[Christian Thalinger]

> On Nov 15, 2015, at 10:39 AM, Kim Barrett <kim.barrett at oracle.com> wrote:
> 
> Please review this cleanup of the API for accessing member offset
> information for SATBMarkQueue and DirtyCardQueue.  Clients now access
> the specific queue class information.  In addition, JVMCI now uses the
> same API for obtaining the information as is used by other compilers
> and interpreters.

The JVMCI changes look good.  To verify run test/compiler/jvmci/.

> 
> Also moved the vmStruct declarations for PtrQueue and members to
> vmStructs_g1.hpp, as that class is G1-specific.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8143014
> 
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8143014/webrev.00/
> 
> Testing:
> JPRT
>