RFR: 8324242: Avoid null check for OopHandle::ptr_raw() [v3]

[Kim Barrett]

> Please review this change to use OopHandle::is_empty() rather than comparing
> the result of OopHandle::ptr_raw() with nullptr.  While equivalent, the former
> is the intended API for such checks.  ptr_raw should only be used directly
> where it is actually needed.
> 
> Testing: mach5 tier1.

Kim Barrett 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:

 - Merge branch 'master' into avoid-ptr-raw-compare
 - tidy CLD remove_handle
 - prefer is_empty

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17510/files
  - new: https://git.openjdk.org/jdk/pull/17510/files/19905134..d02781fb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17510&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17510&range=01-02

  Stats: 2190 lines in 125 files changed: 1498 ins; 373 del; 319 mod
  Patch: https://git.openjdk.org/jdk/pull/17510.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17510/head:pull/17510

PR: https://git.openjdk.org/jdk/pull/17510