[jdk21u-dev] RFR: 8330094: RISC-V: Save and restore FRM in the call stub

[Gui Cao]

Hi, The same issue also exists in JDK21u. So I would like to backport 8330094 to jdk21u-dev. With this change, we save and restore the default floating-point control state when we enter and leave Java code, ensuring that we are still Java compatible if we're called via the JNI invocation interface with a weird FP control state. RISC-V specific change, risk is low.

### Testing

- [x]  Run tier1 tests on SOPHON SG2042 (release)

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Commit messages:
 - Backport 8330094: RISC-V: Save and restore FRM in the call stub

Changes: https://git.openjdk.org/jdk21u-dev/pull/545/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=545&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330094
  Stats: 34 lines in 3 files changed: 21 ins; 9 del; 4 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/545.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/545/head:pull/545

PR: https://git.openjdk.org/jdk21u-dev/pull/545