[jdk23u] RFR: 8337753: Target class of upcall stub may be unloaded [v2]

[Jorn Vernee]

> Backport of: https://github.com/openjdk/jdk/pull/20479
> 
> There were some trivial conflicts in `stubGenerator_aarch64.cpp` and `stubGenerator_riscv.cpp`. Some code still there in jdk23, already removed in later versions.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  Remove code unrelated to fix

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

Changes:
  - all: https://git.openjdk.org/jdk23u/pull/163/files
  - new: https://git.openjdk.org/jdk23u/pull/163/files/c2be7786..121d764b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk23u&pr=163&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk23u&pr=163&range=00-01

  Stats: 28 lines in 4 files changed: 2 ins; 21 del; 5 mod
  Patch: https://git.openjdk.org/jdk23u/pull/163.diff
  Fetch: git fetch https://git.openjdk.org/jdk23u.git pull/163/head:pull/163

PR: https://git.openjdk.org/jdk23u/pull/163