[jdk11u-dev] RFR: 8298129: Let checkpoint event sizes grow beyond u4 limit

[Ekaterina Vergizova]

I'd like to backport JDK-8298129 to 11u.
It fixes corrupted jfr dumps that can be generated for applications with a large stack trace pool or string pool. Such dumps can not be read by jfr tool or JMC.

17u patch doesn't apply cleanly, minor modifications required:
- jfrCheckpointManager.cpp: is_flushpoint and flushpoint_offset were replaced by checkpoint_type and checkpoint_type_offset by JDK-8226511 that is not backported to 11u. Adapted the changes for flushpoint. Additionally nullptr was replaced with NULL since JDK-8246032 is not backported to 11u
- jfrEncoders.hpp, jfrWriterHost.hpp, jfrWriterHost.inline.hpp: copyright years, minor context difference due to #endif comment, reapplied manually
- ChunkParser.java: minor context difference for the second hunk since JDK-8226511 is not backported to 11u, reapplied manually

Tested with tier1 and jdk/jfr tests.

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Commit messages:
 - Backport ea108f504ccb63fc9651e804e3bbba1c108dcead

Changes: https://git.openjdk.org/jdk11u-dev/pull/1708/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1708&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298129
  Stats: 114 lines in 6 files changed: 80 ins; 12 del; 22 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1708.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1708/head:pull/1708

PR: https://git.openjdk.org/jdk11u-dev/pull/1708