RFR: 8356127: (fs) UnixFileSystemProvider.implDelete could save a syscall in some cases [v4]

[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: Fix logic of EISDIR handling

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/25107/files
  - new: https://git.openjdk.org/jdk/pull/25107/files/3814a184..e1b8861b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25107&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25107&range=02-03

  Stats: 12 lines in 1 file changed: 3 ins; 5 del; 4 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