RFR: New issue and fix for problem with AArch64 stack saves/copies

[Andrew Dinn]

I discovered a problem in the AArch64 code which saves/copies sort or
byte values to/between stack slots which I would like to be reviewed
and. hopefully, pulled. I created a git issue and PR for them here

  https://github.com/graalvm/graal/issues/236
  https://github.com/graalvm/graal/pull/237

n.b. This problem existed before PR #233 was pulled. However that PR
made it much more likely to manifest. Unfortunately, the unit tests did
not provide enough coverage of stack operations to trigger the failure
either before or after pull of PR #233. The fix includes a unit test
which manifests the problem (with or without PR #233).

Testing:
With this patch all unit tests pass (including the new one that it adds,
obviously :-).

n.b.b. Travis is currently hosed again thanks to release of jdk-9+177. I
had to update the patch to bump the jdk9 version number up to 197 in
both .travis.yml and in JVCMIVersionCheck.java so as to get the PR to build.

regards,


Andrew Dinn
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Senior Principal Software Engineer
Red Hat UK Ltd
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