[clang] [clang-tools-extra] [compiler-rt] [lldb] [llvm] [mlir] [openmp] [polly] fix(python): fix comparison to None (PR #91857)

[Eisuke Kawashima via cfe-commits]

e-kwsm wrote:

>From [PEP8](https://peps.python.org/pep-0008/#programming-recommendations):

> Comparisons to singletons like None should always be done with `is` or `is not`, never the equality operators.

[flake8](https://flake8.pycqa.org/en/latest/) is used here.


https://github.com/llvm/llvm-project/pull/91857