RFR: 8346787: Fix two C2 IR matching tests for RISC-V [v3]

[Fei Yang]

> Two IR matching tests added by [JDK-8332268](https://bugs.openjdk.org/browse/JDK-8332268) are failing on RISC-V:
>   TEST: compiler/c2/irTests/ModINodeIdealizationTests.java
>   TEST: compiler/c2/irTests/ModLNodeIdealizationTests.java
> 
> These two tests require conditional move support. See ModLNode::Ideal & ModLNode::Ideal [1][2]. But RISC-V base ISA (RV64GCV) does not support conditional move, so we set `ConditionalMoveLimit` to 0 for this CPU platform. This change simply skips these two tests for now.
> 
> Some further information:
> An initial version of conditional move based on RISC-V `Zicond` extension has been added by: [JDK-8344306](https://bugs.openjdk.org/browse/JDK-8344306). But that still lacks performance tunning and we will reconsider and adjust this `ConditionalMoveLimit` parameter as we go. New issue: [JDK-8346786](https://bugs.openjdk.org/browse/JDK-8346786).
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/divnode.cpp#L993
> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/divnode.cpp#L1253

Fei Yang has updated the pull request incrementally with one additional commit since the last revision:

  Comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22874/files
  - new: https://git.openjdk.org/jdk/pull/22874/files/27884e81..c6302209

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22874&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22874&range=01-02

  Stats: 10 lines in 2 files changed: 4 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/22874.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22874/head:pull/22874

PR: https://git.openjdk.org/jdk/pull/22874