RFR: 8322815: Eliminate -Wparentheses warnings in shenandoah code

[Kim Barrett]

8322815: Eliminate -Wparentheses warnings in shenandoah code

Please review this change to eliminate some -Wparentheses warnings. This
involved simply adding a few parentheses to make some implicit operator
precedence explicit.

Testing: local (linux-x64) build with shenandoah included and ran
hotspot:tier1 with -XX:+UseShenandoahGC.

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Commit messages:
 - fix -Wparentheses warnings in shenandoah code

Changes: https://git.openjdk.org/jdk/pull/17214/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17214&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322815
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17214.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17214/head:pull/17214

PR: https://git.openjdk.org/jdk/pull/17214