RFR: 8368633: (fs) Path.toRealPath(NOFOLLOW_LINKS) very slow on macOS [v3]

[Brian Burkhalter]

> Try to avoid checking file keys for all entries by first attempting `Path.compareTo` and `String.equalsIgnoreCase`.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8368633: Compare keys using a second DirectoryStream; improve micro

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27709/files
  - new: https://git.openjdk.org/jdk/pull/27709/files/5412b625..88b33417

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27709&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27709&range=01-02

  Stats: 98 lines in 2 files changed: 79 ins; 8 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/27709.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27709/head:pull/27709

PR: https://git.openjdk.org/jdk/pull/27709