RFR: 8352897: RISC-V: Change default value for UseConservativeFence

[Fei Yang]

On Tue, 25 Mar 2025 15:49:40 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> Hi, please consider.
> 
> gcc have stopped emitting io-bits for fences since 13.
> And we need to use newer gcc due to other compiler bugs.
> Therefore there is no point in letting JIT emit io-bits when the runtime don't have them.
> 
> Thanks, Robbin

Looks good.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24233#pullrequestreview-2715706809