RFR: 8288971: AArch64: Clean up stack and register handling in interpreter

[Andrew Haley]

There are several places in the interpreter that could be improved.

1. We use r13 to pass the caller's SP to a callee through adapters. r13 is not a callee-saved register in the native ABI, so this causes some complications. Use a callee-saved register.
2. We frequently recalculate the location where the native SP needs to go. We have a spare slot in the interpreter frame, so we should calculate it once, when the frame is created, and use it.
3. Related to 1, we should clearly label all the places where the caller's SP is passed to a callee.

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Commit messages:
 - 8288971: AArch64: Clean up stack and register handling in interpreter
 - 8288971: AArch64: Clean up stack and register handling in interpreter

Changes: https://git.openjdk.org/jdk/pull/9239/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9239&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288971
  Stats: 156 lines in 14 files changed: 67 ins; 36 del; 53 mod
  Patch: https://git.openjdk.org/jdk/pull/9239.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9239/head:pull/9239

PR: https://git.openjdk.org/jdk/pull/9239