RFR: Load coops base shift from AOTRuntimeConstants in AOT code

[Andrew Dinn]

This PR modifies AOT compiled method code to load compressed oops base and shift constants via the AOTRuntimeConstants area rather than encode them as immediates. It also unlatches the currently forced setting of UseCompatibleCompressedOops, allowing the heap to be allocated wherever it will fit.

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Commit messages:
 - Store and load CompressedOops base/shift via AOTRuntimeConstants on aarch64
 - Use AOTRuntimeConstants to store and load CompressedOops base and shift

Changes: https://git.openjdk.org/leyden/pull/20/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=20&range=00
  Stats: 269 lines in 9 files changed: 245 ins; 0 del; 24 mod
  Patch: https://git.openjdk.org/leyden/pull/20.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/20/head:pull/20

PR: https://git.openjdk.org/leyden/pull/20