RFR: 7950: Better DisjointBuilder performance for events not ordered by event end attribute

[Richard Startin]

7950: Better DisjointBuilder performance for events not ordered by event end attribute

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Commit messages:
 - 7950: Better DisjointBuilder performance for events not ordered by event end attribute

Changes: https://git.openjdk.org/jmc/pull/450/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=450&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-7950
  Stats: 230 lines in 10 files changed: 82 ins; 133 del; 15 mod
  Patch: https://git.openjdk.org/jmc/pull/450.diff
  Fetch: git fetch https://git.openjdk.org/jmc pull/450/head:pull/450

PR: https://git.openjdk.org/jmc/pull/450