RFR: 8328112: Remove CardTable::_guard_region [v3]

[Guoxiong Li]

> Hi all,
> 
> This patch removes the `CardTable::_guard_region`. Thanks for taking the time to review.
> 
> Best Regards,
> -- Guoxiong

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

  Leave var  num_bytes.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18324/files
  - new: https://git.openjdk.org/jdk/pull/18324/files/c0a74704..393c2e38

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18324&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18324&range=01-02

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18324.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18324/head:pull/18324

PR: https://git.openjdk.org/jdk/pull/18324