RFR: 8297875: jar should not compress the manifest directory entry

[Liam Miller-Cushon]

This causes jar to not compress the `META-INF/` directory entry, for consistency with the handling of other directory entries and compliance with `APPNOTE.TXT`, and for compatibility with other zip implementations.

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Commit messages:
 - 8297875: jar should not compress the manifest directory entry

Changes: https://git.openjdk.org/jdk/pull/11441/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11441&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297875
  Stats: 87 lines in 2 files changed: 87 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11441.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11441/head:pull/11441

PR: https://git.openjdk.org/jdk/pull/11441