RFR: 8336924: Disable jcheck for referencing an issue number in commit message title.

[Man Cao]

Hi all,

https://github.com/openjdk/tsan/pull/19 sees a jcheck error "The commit message does not reference any issue. To add an issue reference to this PR, edit the title to be of the format issue number: message."
TSAN project currently does not need an issue for a commit, so I propose we disable this check.

The jcheck was probably enabled in Sep, 2020 by https://github.com/openjdk/tsan/commit/e0c8d4420c8e1a84581927cf77314498b8e5aa52.  However, TSAN project did not have new PRs except merges after Sep, 2020. (I think this check probably skips checking merge commits and merge PRs.)

-Man

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Commit messages:
 - Disable jcheck for referencing an issue number in commit message title.

Changes: https://git.openjdk.org/tsan/pull/20/files
  Webrev: https://webrevs.openjdk.org/?repo=tsan&pr=20&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336924
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/tsan/pull/20.diff
  Fetch: git fetch https://git.openjdk.org/tsan.git pull/20/head:pull/20

PR: https://git.openjdk.org/tsan/pull/20