RFR: 8209345: Merge SATBMarkQueueFilter into SATBMarkQueueSet

[Kim Barrett]

Please review this change that eliminates SATBMarkQueueFilter in favor
of an extension to SATBMarkQueueSet.  The QSet's _filter member and
filter function that invokes it are replaced by a virtual function on
the QSet.  G1SATBMarkQueueSet provides an implementation copied from
the former G1SATBMarkQueueFilter.

Changed SATBMarkQueueSet's constructor and destructor from public to
protected, since it's a base class.  Also made initialize protected,
as it should only be called from derived classs.

This changeset is based on the in-review change for JDK-8209396.
http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2018-August/022868.html

CR:
https://bugs.openjdk.java.net/browse/JDK-8209345

Webrev:
http://cr.openjdk.java.net/~kbarrett/8209345/open.00/

Testing:
Mach5 tier1-3, hs-tier4-5, in conjunction with JDK-8209346 and JDK-8209347.
Locally tier1 and hotspot_gc without those other changes.