[riscv-port] RFR: 8278832: riscv: Inconsistency of Java frame offset definition in jdk.hotspot.agent

[Feilong Jiang]

The Java frame definition was refactored in https://github.com/openjdk/jdk-sandbox/commit/db2415748747a0912749bb8fc160a8948021a924 to make Java frame offset the same as C frame. In jdk.hotspot.agent, there is another Java frame definition based on the old Java frame offset, which causes jstack stack walking error. These definitions should also be updated.

Two tests passed after this fixing:
- test/hotspot/jtreg/serviceability/sa/ClhsdbCDSCore.java
- test/hotspot/jtreg/serviceability/sa/ClhsdbFindPC.java

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Commit messages:
 - 8278832: riscv: Inconsistency of Java frame offset definition in jdk.hotspot.agent

Changes: https://git.openjdk.java.net/riscv-port/pull/30/files
 Webrev: https://webrevs.openjdk.java.net/?repo=riscv-port&pr=30&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278832
  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/riscv-port/pull/30.diff
  Fetch: git fetch https://git.openjdk.java.net/riscv-port pull/30/head:pull/30

PR: https://git.openjdk.java.net/riscv-port/pull/30