RFR: 8272231 G1: Refactor G1CardSet::get_card_set to return G1CardSetHashTableValue* [v2]

[Ivan Walulya]

> Hi all,
> 
> Please review this change to return G1CardSetHashTableValue* from G1CardSet::get_card_set. Consequently, we do not have to use G1CardSet::get_or_add_card_set in instances where we only need to get the table entry (such as in G1CardSet::transfer_cards_in_howl).
> 
> Testing: Tier 1-5.

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

  Kim review

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5072/files
  - new: https://git.openjdk.java.net/jdk/pull/5072/files/1a0ffeed..02039d48

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5072&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5072&range=00-01

  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5072.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5072/head:pull/5072

PR: https://git.openjdk.java.net/jdk/pull/5072