[Rev 01] RFR: Add support for building on AArch64

[Nick Gasson]

The pull request has been updated with additional changes.

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Added commits:
 - 0417521a: Correct value of os.arch on Mac

Changes:
  - all: https://git.openjdk.java.net/skara/pull/231/files
  - new: https://git.openjdk.java.net/skara/pull/231/files/fd6a7291..0417521a

Webrevs:
 - full: https://webrevs.openjdk.java.net/skara/231/webrev.01
 - incr: https://webrevs.openjdk.java.net/skara/231/webrev.00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/231.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/231/head:pull/231

PR: https://git.openjdk.java.net/skara/pull/231