RFR: change AArch64 address plan to prefer scaled addressing

[Andrew Dinn]

This PR is available to review and (now Travis is back again) ready to pull:

  https://github.com/graalvm/graal/pull/233

As explained in the PR it's a cosmetic change to improve readability of
generated code.

Could someone please review it?

regards,


Andrew Dinn
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Senior Principal Software Engineer
Red Hat UK Ltd
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