RFR: 8365166: ARM32: missing os::fetch_bcp_from_context implementation [v2]

[Aleksey Shipilev]

On Wed, 13 Aug 2025 00:07:26 GMT, Boris Ulasevich <bulasevich at openjdk.org> wrote:

>> Since [JDK-8352251](https://bugs.openjdk.org/browse/JDK-8352251) (JEP 518: JFR Cooperative Sampling), jfrSampleRequest calls os::fetch_bcp_from_context(). On ARM32 port it is still Unimplemented(). It should read the corresponding field from uc_mcontext and return the BCP value.
>
> Boris Ulasevich has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp
>   
>   Co-authored-by: Aleksey Shipilëv <shipilev at amazon.de>

Huh, I wonder how the review was lost...

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26699#pullrequestreview-3115853061