RFR: 8289698: AArch64: Need to relativize extended_sp in frame

[Andrew Haley]

With the addition of the extended_sp field in interpreter frames, we need to make sure it is de-relativized and re-relativized when freezing and thawing a vthread.

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Commit messages:
 - 8289698: AArch64: Need to relativize extended_sp in frame

Changes: https://git.openjdk.org/jdk/pull/9367/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9367&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289698
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9367.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9367/head:pull/9367

PR: https://git.openjdk.org/jdk/pull/9367