[jdk25u] RFR: 8359270: C2: alignment check should consider base offset when emitting arraycopy runtime call

[Fei Yang]

Hi all,

This pull request contains a backport of commit [6b439391](https://github.com/openjdk/jdk/commit/6b4393917ae689818d67fcaf9cc61ca16ea6d426) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Fei Yang on 23 Jun 2025 and was reviewed by Tobias Hartmann and Vladimir Kozlov.

Thanks!

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

Commit messages:
 - Backport 6b4393917ae689818d67fcaf9cc61ca16ea6d426

Changes: https://git.openjdk.org/jdk25u/pull/6/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u&pr=6&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359270
  Stats: 136 lines in 3 files changed: 128 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk25u/pull/6.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u.git pull/6/head:pull/6

PR: https://git.openjdk.org/jdk25u/pull/6