RFR: 8356127: (fs) UnixFileSystemProvider.implDelete could save a syscall in some cases [v5]

[Brian Burkhalter]

> Modify `UnixFileSystemProvider.implDelete` to attempt first to delete the file using `unlink` and, if that fails, fall back to using `rmdir` if the file is a directory.

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

  8356127: Tweak previous commit

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Changes:
  - all: https://git.openjdk.org/jdk/pull/25107/files
  - new: https://git.openjdk.org/jdk/pull/25107/files/e1b8861b..6cb746b2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25107&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25107&range=03-04

  Stats: 4 lines in 1 file changed: 1 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25107.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25107/head:pull/25107

PR: https://git.openjdk.org/jdk/pull/25107