[jdk16u] RFR: 8258909: update jdk16u jcheck conf

[Rob McKenna]

The jdk16u repository is forked from the jdk16 stabilization repository. The jcheck configuration should be updated post-fork to indicate that this repository is part of the jdk-updates project.

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Commit messages:
 - 8258909: update jdk16u jcheck conf

Changes: https://git.openjdk.java.net/jdk16u/pull/1/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16u&pr=1&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258909
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk16u/pull/1.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16u pull/1/head:pull/1

PR: https://git.openjdk.java.net/jdk16u/pull/1