RFR: 8340838: Clean up MutableCallSite to use explicit release fence instead of AtomicInteger

[John R Rose]

On Tue, 24 Sep 2024 20:21:48 GMT, Chen Liang <liach at openjdk.org> wrote:

> This implementation code was written in JDK 7, before storeFence was available in JDK 8. We should update this legacy code to make it clear.

Good, thank you.  Nice to see that silly variable go away.

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

Marked as reviewed by jrose (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21169#pullrequestreview-2326485048