RFR: 8292562: (fc) Use copy_file_range in FileChannel::transferTo on Linux [v5]

[Brian Burkhalter]

> Add `copy_file_range(2)` to the native Linux implementation of `FileChannel::transferTo`.

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

  8292562: Add append parameter; add transferFrom to test

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9925/files
  - new: https://git.openjdk.org/jdk/pull/9925/files/c3c36f1d..34e03520

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9925&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9925&range=03-04

  Stats: 70 lines in 4 files changed: 18 ins; 10 del; 42 mod
  Patch: https://git.openjdk.org/jdk/pull/9925.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9925/head:pull/9925

PR: https://git.openjdk.org/jdk/pull/9925