Modify the PacketTransmissionTask to update the current deadline (`now`) between loop iterations.
This fixes the deadlock issue which happened when the next deadline was equal to the current one, but no progress could be made because the pacer quota only increases as time passes. No new test; the issue was extremely rare. Existing tests continue to pass. ------------- Commit messages: - Fix deadlock in packet transmission task Changes: https://git.openjdk.org/jdk/pull/28462/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28462&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8372344 Stats: 10 lines in 1 file changed: 2 ins; 1 del; 7 mod Patch: https://git.openjdk.org/jdk/pull/28462.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/28462/head:pull/28462 PR: https://git.openjdk.org/jdk/pull/28462
