RFR: 8296773: G1: Common hash function for G1CardSet

[Thomas Schatzl]

Hi all,

  please review this refactoring that removes the inlining of the "hash" in `G1CardSet` to call a common function.
This makes experimenting with different hash functions much easier.

Testing: local compilation, gha

Thanks,
  Thomas

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Commit messages:
 - refactoring

Changes: https://git.openjdk.org/jdk/pull/11087/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11087&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296773
  Stats: 35 lines in 2 files changed: 20 ins; 14 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/11087.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11087/head:pull/11087

PR: https://git.openjdk.org/jdk/pull/11087