RFR: 8316000: File.setExecutable silently fails if file does not exist [v6]

[Brian Burkhalter]

> On Windows, do not return `true` from the `java.io.File` methods `setReadable(boolean, boolean)` and `setExecutable(boolean, boolean)` if the file does not exist.

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

  8316000: Revert specification verbiage and modify @return description

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15673/files
  - new: https://git.openjdk.org/jdk/pull/15673/files/8189784a..2ec7d229

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15673&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15673&range=04-05

  Stats: 30 lines in 1 file changed: 4 ins; 0 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/15673.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15673/head:pull/15673

PR: https://git.openjdk.org/jdk/pull/15673