RFR: 8368724: RISC-V: Check if unaligned_access is enabled before use

[Hamlin Li]

On Fri, 26 Sep 2025 03:36:50 GMT, Anjian Wen <wenanjian at openjdk.org> wrote:

> we can notice that the `unaligned_access.value()` can only be used when the `unaligned_access.enabled()` is true, so we add the check here before use
> 
> Manually checked the result on platforms w/wo fast misaligned accesses by running: $java -XX:+PrintFlagsFinal -version | grep AvoidUnalignedAccess

I think we're going to remove the `AvoidUnalignedAccesses`? And if `unaligned_access` is not enabled, then its value can not be `MISALIGNED_FAST`?
If both above are true, then seems this check is not necessary?

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PR Comment: https://git.openjdk.org/jdk/pull/27510#issuecomment-3337362224