RFR: 8360936: Test compiler/onSpinWait/TestOnSpinWaitAArch64.java fails after JDK-8359435 [v4]

[Evgeny Astigeevich]

On Wed, 9 Jul 2025 08:27:46 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> @theRealAph, are you okay with the latest variant Aleksey proposes?
>
>> But this is a generic macroAssembler block comment. It does not make sense to me to have a block comment that looks like a memory corrupted string, just to satisfy a single test. There should be a middle-ground here, e.g. `spin_wait {`, which looks reasonably enough as the block comment, and not anything else. Would also match nicely when we emit the closing `}` at the end of the instruction block.
> 
> OK

I update the PR to use `spin_wait { ... }`

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PR Review Comment: https://git.openjdk.org/jdk/pull/26072#discussion_r2195023640