RFR: 8356030: RISC-V: enable (part of) BasicDoubleOpTest.java

[Hamlin Li]

Hi,
Can you help to review this patch?
Originally, I was going to enable all test cases on riscv in this test file. But seems there was already a try to implement RoundDoubleModeV (which is IRNode.ROUND_DOUBLE_MODE_V) in https://github.com/openjdk/jdk/pull/21164, but failed because of some performance regression.
So I'll just enable part of test cases in this pr.

Thanks!

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Commit messages:
 - not enable RoundDoubleModeV
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/24983/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24983&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8356030
  Stats: 24 lines in 1 file changed: 13 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/24983.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24983/head:pull/24983

PR: https://git.openjdk.org/jdk/pull/24983