[jdk21u-dev] RFR: 8337780: RISC-V: C2: Change C calling convention for sp to NS

[Fei Yang]

8337780: RISC-V: C2: Change C calling convention for sp to NS

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Commit messages:
 - Backport 53db937dd0766695906dc20c1dbbd3228c02fe1e

Changes: https://git.openjdk.org/jdk21u-dev/pull/945/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=945&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337780
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/945.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/945/head:pull/945

PR: https://git.openjdk.org/jdk21u-dev/pull/945