RFR: 8277372: Add getters for BOT and card table members [v6]

[Vishal Chand]

> Changed the visibility, added getters and refactored the following:
> 
> 1. Card Table Members
> 2. BOT members
> 3. ObjectStartArray block members

Vishal Chand has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Merge branch 'master' into JDK-8277372-refactor
 - Rename BOTConstants and ObjectStartArray members to _card_*
 - Rename BOTConstants
 - Merge branch 'master' into JDK-8277372-refactor
 - Refactoring in hotspot/cpu dir
 - Initial patch

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Changes: https://git.openjdk.java.net/jdk/pull/6570/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6570&range=05
  Stats: 217 lines in 40 files changed: 41 ins; 12 del; 164 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6570.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6570/head:pull/6570

PR: https://git.openjdk.java.net/jdk/pull/6570