_controlfp_s: Describe effects of FPCR changes on ARM

[olologin]

We believe this note should be somewhere close to _controlfp_s documentation.
More details:
https://stackoverflow.com/questions/78917793/windows-on-arm-math-is-not-trapping

[prmerger-automator]

@olologin : Thanks for your contribution! The author(s) have been notified to review your proposed change.

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[Court72]

@TylerMSFT

Can you review the proposed changes?

Important: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team

[TylerMSFT]

Hi, we are looking into this.

[olologin]

Of course it is better to make it possible to enable exception handling, at least optionally. Because it doesn't look like a good idea to disable them for all ARM CPUs without a way to enable them, just because some ARM CPUs don't support it.

But that is not documentation-related.

[TylerMSFT]

@olologin , I am closing this but the reason is that the change affects another file as well. I'm working with the product team on this and want to get the changes all in one PR. I'll notify you via this closed PR when that's done so you can see the change.

[TylerMSFT]

@olologin, I updated three docs which will be live by noon (PST) 4/25
Overview of ARM64 ABI conventions
Overview of ARM64EC ABI conventions
_controlfp_s

PR#5850