RFR: 8324514: ClassLoaderData::print_on should print address of class loader [v3]

[Aleksey Shipilev]

> This looks like a simple diagnostic regression from [JDK-8201556](https://bugs.openjdk.org/browse/JDK-8201556). Instead of printing the address of the `OopHandle` slot, we really want to print the address of the classloader that handle holds. That was not intentional, right, @coleenp?
> 
> I think we can `peek()` into handle, but the whole reason for [JDK-8201556](https://bugs.openjdk.org/browse/JDK-8201556) seems to avoid touching the classloader oops when unloading, and `peek()` would do a GC barrier on it. We could specialize for `!unloading` path, but I think we still want to see what is in the handle. So, this PR introduces the "peek_raw" version that would compile straight to plain access, after the null check.

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  peek_raw

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17534/files
  - new: https://git.openjdk.org/jdk/pull/17534/files/bbe49f09..dca07884

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17534&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17534&range=01-02

  Stats: 10 lines in 3 files changed: 5 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17534.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17534/head:pull/17534

PR: https://git.openjdk.org/jdk/pull/17534