<AWT Dev> RFR: 8256109: Create implementation for NSAccessibilityButton protocol [v4]

[Alexander Zuev]

> Creating a native peer for pushbutton accessibility role on Max OS X.
> The process of choosing of what peer to initialize is clunky so
> might be addressed in the future.

Alexander Zuev has updated the pull request incrementally with two additional commits since the last revision:

 - Fixed year in .h files
 - Update code to use new style JNI

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1549/files
  - new: https://git.openjdk.java.net/jdk/pull/1549/files/d9d6f754..38d54d04

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1549&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1549&range=02-03

  Stats: 95 lines in 5 files changed: 26 ins; 47 del; 22 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1549.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1549/head:pull/1549

PR: https://git.openjdk.java.net/jdk/pull/1549