RFR: 8258255: Move PtrQueue active flag to SATBMarkQueue

[Kim Barrett]

Please review this change to the PtrQueue hierarchy, moving the support for
"active" queues and qset to SATBMarkQueue[Set], which is the only user of
this feature.  Other classes derived from PtrQueue[Set] currently work
around or ignore this feature.  This change removes it from consideration
entirely for those other classes.

Testing:
mach5 tier1
local (linux-x64) hotspot:tier1 with -XX:+UseShenandoahGC

In the process of doing this refactoring I noticed that some of the
vmStructs support around PtrQueue[Set] didn't get moved from G1 to shared,
and the G1 parts are incomplete.  Filed JDK-8258581 to address that.

-------------

Commit messages:
 - move_active

Changes: https://git.openjdk.java.net/jdk/pull/1820/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1820&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258255
  Stats: 78 lines in 8 files changed: 22 ins; 38 del; 18 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1820.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1820/head:pull/1820

PR: https://git.openjdk.java.net/jdk/pull/1820