[jdk8u-dev] RFR: 8375063: Update Libpng to 1.6.54

Mon Feb 16 06:55:02 UTC 2026

Hi all,

This pull request contains a backport of commit [a2e74957](https://github.com/openjdk/jdk/commit/a2e749572e03dd394d123b701e163e3837472dd0) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Jayathirth D V on 21 Jan 2026 and was reviewed by Sergey Bylokhov and Phil Race.

The backport is mostly clean, I had to update the license in `THIRD_PARTY_README` instead of `libpng.md`.
No new issues found by the :jdk_desktop tests.

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Commit messages:
 - Update THIRD_PARTY_README
 - 8375063: Update Libpng to 1.6.54

Changes: https://git.openjdk.org/jdk8u-dev/pull/760/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=760&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375063
  Stats: 1406 lines in 16 files changed: 443 ins; 7 del; 956 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/760.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/760/head:pull/760

PR: https://git.openjdk.org/jdk8u-dev/pull/760