[Fortran] disable pointer_check_11.f90 which exhibits UB

[tblah]

This test calls an empty subroutine with a null pointer as an argument. In gfortran it is hoped that a flag will detect this and produce an error. Flang does not perform any such analysis, and so on some machines when optimization is enabled, this test never terminates. I don't think this is a flang bug as such because the input code is doing undefined behaviour.

This is a cherry-pick of #232 to the 20.x release branch. I'm not sure how this works for llvm-test-suite as there appears to be no bot.

[tblah]

@tstellar is this allowed? Is there a process that should be followed here?

I'm not sure how the releases work for llvm-test-suite

[pawosm-arm]

For me it looks OK, I experienced it when working with the release/20.x branch, so I'm interested in it being cherry-picked.

[DavidTruby]

I think there shouldn't be an issue merging to the release branch for the test suite? @tarunprabhu do you have an opinion since you reviewed this patch for the main branch?

[tarunprabhu]

I think there shouldn't be an issue merging to the release branch for the test suite? @tarunprabhu do you have an opinion since you reviewed this patch for the main branch?

I don't think that merging it into the release branch should cause any problems. But I also don't know if there is a precedent or process to be followed for doing this in the test-suite. I'm happy to approve this, conditional on getting an ok from someone who knows more about the test suite's policies.