RFR: 8265119: G1: update_remset_before_rebuild mixes liveness in words with liveness in bytes [v2]

[Ivan Walulya]

> Hi all,
> 
> Please review this change to rename ConcurrentMark::liveness() to live_words() making it clear that this represents the number of live words between bottom and nTAMS. Adding ConcurrentMark::live_bytes() to return the same value in bytes. Additionally, I add a test for G1MixedGCLiveThresholdPercent flag.
> 
> Testing: tier 1-5.

Ivan Walulya has updated the pull request incrementally with one additional commit since the last revision:

  changes proposed by Thomas review

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3511/files
  - new: https://git.openjdk.java.net/jdk/pull/3511/files/924f9ffe..1803f998

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3511&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3511&range=00-01

  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3511.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3511/head:pull/3511

PR: https://git.openjdk.java.net/jdk/pull/3511