Graphcut tests sporadically fail on MacOS

[joeljonsson]

I have tried setting up the github actions workflow to use

• AppleClang 13
• gcc 11 (homebrew)
• llvm clang (homebrew)

but the issue persists. Testing locally (with AppleClang 12), it appears that the issue is related to OpenMP, as the tests consistently passed with OpenMP disabled. With OpenMP, any of the test cases may pass or fail seemingly at random.

For the time being, I will add a skip for this test on MacOS.