RFR: 8325082: Rename headers named 'heapRegion*' of G1 [v2]

[Lei Zaakjyu]

> 8325082: Rename headers named 'heapRegion*' of G1

Lei Zaakjyu has updated the pull request incrementally with one additional commit since the last revision:

  reorder some headers

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17666/files
  - new: https://git.openjdk.org/jdk/pull/17666/files/2d38a1b7..7d105a58

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17666&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17666&range=00-01

  Stats: 146 lines in 51 files changed: 73 ins; 73 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/17666.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17666/head:pull/17666

PR: https://git.openjdk.org/jdk/pull/17666