Remove unused declarations from net_util. Move include declarations to the files that require them.
Tier1-2 clean. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - Clean up SDK references - Remove DatagramPacket-related declarations - Remove unused defines Changes: https://git.openjdk.org/jdk/pull/33365/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=33365&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8394574 Stats: 108 lines in 10 files changed: 9 ins; 97 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/33365.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/33365/head:pull/33365 PR: https://git.openjdk.org/jdk/pull/33365
