RFR: 8276930: Update ProblemList

[Jesper Wilhelmsson]

Update a few entries in the problemlist that refer to bugs that have been closed as duplicates.

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Commit messages:
 - Fixed duplicates

Changes: https://git.openjdk.java.net/jdk/pull/6328/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6328&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276930
  Stats: 8 lines in 1 file changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6328.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6328/head:pull/6328

PR: https://git.openjdk.java.net/jdk/pull/6328