[jdk11u-dev] RFR: 8291638: Keep-Alive timeout of 0 should close connection immediately

[Goetz Lindenmaier]

I backport this for parity with 11.0.20-oracle.

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Commit messages:
 - Backport 26ac8366360685ef0cf3447ee7db16ba7a7fa1ec

Changes: https://git.openjdk.org/jdk11u-dev/pull/1821/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1821&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291638
  Stats: 40 lines in 4 files changed: 29 ins; 8 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1821.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/1821/head:pull/1821

PR: https://git.openjdk.org/jdk11u-dev/pull/1821