RFR: 8289138: G1: Remove redundant is-marking-active checks in C1 barrier

Fri Jun 24 12:09:08 UTC 2022

Simple change of removing a redundant check in C1 barrier code.

Test: tier1-3

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Commit messages:
 - g1-c1-remove-mark-check

Changes: https://git.openjdk.org/jdk/pull/9274/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9274&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289138
  Stats: 51 lines in 6 files changed: 0 ins; 51 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9274.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9274/head:pull/9274

PR: https://git.openjdk.org/jdk/pull/9274