RFR: 6701: Supporting LZ4 compressed recordings

[Marcus Hirt]

What is says in the PR title. ;)

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Commit messages:
 - Adding thirdpartyreadme entry for lz4-java
 - 6701: Supporting LZ4 compressed recordings

Changes: https://git.openjdk.java.net/jmc/pull/65/files
 Webrev: https://webrevs.openjdk.java.net/jmc/65/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6701
  Stats: 354 lines in 18 files changed: 322 ins; 11 del; 21 mod
  Patch: https://git.openjdk.java.net/jmc/pull/65.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/65/head:pull/65

PR: https://git.openjdk.java.net/jmc/pull/65