RFR: 8354477: C2 SuperWord: make use of memory edges more explicit

Thu Apr 17 09:03:55 UTC 2025

This is a small refactoring, to make it more explicit that the "additional dependencies" are memory dependencies.

This is also preparatory work for [JDK-8324751](https://bugs.openjdk.org/browse/JDK-8324751), where we have two memory edge categories: strong and weak.

I was able to pass around `vtn_dependencies` in fewer occasions, and also renamed it to `vtn_memory_dependencies`.

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Commit messages:
 - simplify and rename
 - JDK-8354477

Changes: https://git.openjdk.org/jdk/pull/24613/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24613&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354477
  Stats: 75 lines in 5 files changed: 20 ins; 13 del; 42 mod
  Patch: https://git.openjdk.org/jdk/pull/24613.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24613/head:pull/24613

PR: https://git.openjdk.org/jdk/pull/24613