[lilliput-jdk21u:lilliput] RFR: 8319524: [Lilliput] Only warn when compact headers are explicitly enabled

[Roman Kennke]

Hi all,

This pull request contains a backport of commit [3f73f014](https://github.com/openjdk/lilliput/commit/3f73f014097262455cc42a71c32af374b77b6efd) from the [openjdk/lilliput](https://git.openjdk.org/lilliput) repository.

The commit being backported was authored by Roman Kennke on 6 Nov 2023 and was reviewed by Aleksey Shipilev.

Thanks!

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Commit messages:
 - Backport 3f73f014097262455cc42a71c32af374b77b6efd

Changes: https://git.openjdk.org/lilliput-jdk21u/pull/13/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk21u&pr=13&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319524
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/lilliput-jdk21u/pull/13.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk21u.git pull/13/head:pull/13

PR: https://git.openjdk.org/lilliput-jdk21u/pull/13