RFR: 8368307: Shenandoah: get_next_bit_impl should special case weak and strong mark bits [v2]

[Kelvin Nilsen]

> Check for weak bit or strong bit when giving special handling to the next bit found in first position of word.

Kelvin Nilsen has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Fix up comment
 - Merge remote-tracking branch 'jdk/master' into next-bit-may-be-weak
 - check for weak bit or strong bit in first bit position

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27476/files
  - new: https://git.openjdk.org/jdk/pull/27476/files/d144bdc1..a3700aa0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27476&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27476&range=00-01

  Stats: 13168 lines in 308 files changed: 7595 ins; 3835 del; 1738 mod
  Patch: https://git.openjdk.org/jdk/pull/27476.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27476/head:pull/27476

PR: https://git.openjdk.org/jdk/pull/27476