[jdk17u-dev] RFR: Merge jdk17u:master

[Goetz Lindenmaier]

Merge build tag 17.0.18+7 from jdk17u to jdk17u-dev

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Commit messages:
 - Merge
 - 8372534: Update Libpng to 1.6.51
 - 8317970: Bump target macosx-x64 version to 11.00.00

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=4225&range=00.0
 - jdk17u:master: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=4225&range=00.1

Changes: https://git.openjdk.org/jdk17u-dev/pull/4225/files
  Stats: 658 lines in 23 files changed: 297 ins; 223 del; 138 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/4225.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/4225/head:pull/4225

PR: https://git.openjdk.org/jdk17u-dev/pull/4225