RFR: 8272773: Investigate making card table size configurable [v3]

[Vishal Chand]

> Hi,
> 
> Please review the changes to make CardTable entry size configurable. The changes primarily consists of:
> 
> 1. Addition of a cmdline flag **GCCardSizeInBytes** to make the card size startup time configurable.
> 2. Setting the card size based on the flag in G1, Parallel and Serial GC memory initialization paths.
> 3. Setting BlockOffsetTable size and ObjectStartArray size based on the card size.

Vishal Chand has updated the pull request incrementally with two additional commits since the last revision:

 - Merge branch 'card-size-configurable' of https://github.com/vish-chan/jdk into card-size-configurable
 - Changes as per the first set of comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5838/files
  - new: https://git.openjdk.java.net/jdk/pull/5838/files/83062219..c9c8db81

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5838&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5838&range=01-02

  Stats: 3 lines in 2 files changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5838.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5838/head:pull/5838

PR: https://git.openjdk.java.net/jdk/pull/5838