RFR: 8324242: Avoid null check for OopHandle::ptr_raw() [v2]

[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 incrementally with one additional commit since the last revision:

  tidy CLD remove_handle

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17510/files
  - new: https://git.openjdk.org/jdk/pull/17510/files/f387b8f3..19905134

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17510&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17510&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 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