Fix the osx-arm64 build

[xiki-tempula]

The arm64 mac has $(uname -m) as arm64 not arm
Fix #44

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

I do have some suggestions for making it better though...

For recipe:

• This recipe is using a compiler, which now requires adding a build dependence on {{ stdlib("c") }} as well. For further details, please see META: {{ stdlib("c") }} migration conda-forge.github.io#2102.

[mattwthompson]

IIUC, the Azure runners we have access to never hit proper osx-64 hardware so there isn't a way to really test this

I can at least verify that making this change to my local $CONDA_PREFIX/bin/gmx file (from an existing build) gets a gmx --version working where it previously crashed looking for something with SSE in the path

[xiki-tempula]

I did this change to my local M1 mac and it works now.

[xiki-tempula]

@douglowe @mabraham Shall we consider merging this ASAP? As without this patch none of the arm64 build would work. We might also want to deprecate all the existing arm64 builds as they are all broken.

[mabraham]

I tried to make the match more flexible. If someone can do a local test on Mac ARM, then I think we shoudl merge asap!