Integrated: 7993: Support checkpoint event sizes beyond u4 limit

[Marcus Hirt]

See https://bugs.openjdk.org/browse/JDK-8298129.

-------------

Commit messages:
 - 7993: Support checkpoint event sizes beyond u4 limit

Changes: https://git.openjdk.org/jmc/pull/458/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=458&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-7993
  Stats: 8 lines in 1 file changed: 5 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jmc/pull/458.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/458/head:pull/458

PR: https://git.openjdk.org/jmc/pull/458