RFR: 8256813: Simplify WeakProcessor counting of OopStorage entries [v2]

[Kim Barrett]

> Please review this change to WeakProcessor's counting of weak and dead
> entries.  After JDK-8212879 we no longer need different closure classes to
> deal with the serial and oopstorage cases, since the serial case no longer
> exists.  We can collapse that down to one closure class that is tailored for
> the remaining uses.
> 
> Also deleted a stale comment left over from JDK-8212879.
> 
> Testing:
> mach5 tier1
> Locally (linux-x64) hotspot:tier1 with Serial and Parallel GCs.

Kim Barrett has updated the pull request incrementally with two additional commits since the last revision:

 - stefank_review
 - stefanj_review

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1362/files
  - new: https://git.openjdk.java.net/jdk/pull/1362/files/e8aa8ae8..d6f1cee8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1362&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1362&range=00-01

  Stats: 5 lines in 2 files changed: 2 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1362.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1362/head:pull/1362

PR: https://git.openjdk.java.net/jdk/pull/1362