RFR: 8289689: (fs) Re-examine the need for normalization to Unicode Normalization Format D (macOS)

[Brian Burkhalter]

On macOS, perform file name normalization if and only if a specific system property is set.

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Commit messages:
 - 8289689: (fs) Re-examine the need for normalization to Unicode Normalization Format D (macOS)

Changes: https://git.openjdk.org/jdk/pull/10885/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10885&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289689
  Stats: 41 lines in 3 files changed: 26 ins; 0 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/10885.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10885/head:pull/10885

PR: https://git.openjdk.org/jdk/pull/10885