RFR: 8316523: Relativize esp in interpreter frames (PowerPC only)

[Fredrik Bredberg]

Relativize esp (Expression Stack Pointer on PowerPC) in interpreter frames.

By changing the "esp" member in interpreter frames from being an absolute address into an offset that is relative to the frame pointer, we don't need to change the value as we freeze and thaw frames of virtual threads. This is since we might freeze and thaw from and to different worker threads, so the absolute address to locals might change, but the offset from the frame pointer will be constant.

This subtask only handles "esp" on PowerPC. The relativization of other interpreter frame members are handled in other subtasks to [JDK-8289296](https://bugs.openjdk.org/browse/JDK-8289296).

It has been sanity tested onr PowerPC using Qemu.

-------------

Commit messages:
 - 8316523: Relativize esp in interpreter frames (PowerPC only)
 - 8316523_relativize_esp_on_ppc

Changes: https://git.openjdk.org/jdk/pull/15999/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15999&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316523
  Stats: 23 lines in 4 files changed: 16 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/15999.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15999/head:pull/15999

PR: https://git.openjdk.org/jdk/pull/15999