RFR: 8293122: (fs) Use file cloning in macOS version of Files::copy method [v5]

[Brian Burkhalter]

> Use BSD system call `clonefile` if possible when using `Files::copy` on macOS.

Brian Burkhalter has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge
 - 8293122: Move rollback unlink to copyFile method
 - 8293122: remove volatile cloneFileNotSupported; unlink target on failure; remove getattrlist
 - 8293122: Revert BsdFileStore; move volume capability check to BsdNativeDispatcher
 - 8293122: (fs) Use file cloning in macOS version of Files::copy method

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10188/files
  - new: https://git.openjdk.org/jdk/pull/10188/files/96db8562..afc9c675

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10188&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10188&range=03-04

  Stats: 13721 lines in 304 files changed: 7974 ins; 4716 del; 1031 mod
  Patch: https://git.openjdk.org/jdk/pull/10188.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10188/head:pull/10188

PR: https://git.openjdk.org/jdk/pull/10188