RFR: 8370884: JFR: Overflow in aggregators

[Erik Gahlin]

Could I have a review of a change that fixes overflow issues for the jfr query aggregators?

Testing: jdk/jdk/jfr

Thanks
Erik

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Commit messages:
 - Initial

Changes: https://git.openjdk.org/jdk/pull/28135/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28135&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370884
  Stats: 58 lines in 1 file changed: 46 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/28135.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28135/head:pull/28135

PR: https://git.openjdk.org/jdk/pull/28135