RFR: 8274988 G1: refine G1SegmentedArrayAllocOptions and G1CardSetAllocOptions [v2]

[Hamlin Li]

> This is a follow-up of JDK-8273626. (something mentioned in Description was already done in JDK-8273626)
> Some other cleanups need to be done:
> Some fields of G1SegmentedArrayAllocOptions better be reloated to G1CardSetAllocOptions, and some fields are const, and also adds some assert.

Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:

  remove unnecessary asserts

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6032/files
  - new: https://git.openjdk.java.net/jdk/pull/6032/files/e9235916..c593e311

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6032&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6032&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6032.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6032/head:pull/6032

PR: https://git.openjdk.java.net/jdk/pull/6032