RFR: 8278241: Implement JVM SpinPause on linux-aarch64 [v4]

[Evgeny Astigeevich]

On Tue, 14 Dec 2021 15:01:42 GMT, Andrew Haley <aph at openjdk.org> wrote:

> Two more changes. The first makes the code simpler, and the second makes it less fragile.
> 

Thank you! I forgot `__ spin_wait` generates nothing with `XX:OnSpinWaitInst=none`.

Done.

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PR: https://git.openjdk.java.net/jdk/pull/6803