Merge topic 'FindOpenMP-clang-windows'

3adeb3b470 ci: Enable FindOpenMP tests in LLVM/Clang nightly CI jobs on Windows
3019af64c2 FindOpenMP: Add support for GNU-like Clang targeting MSVC ABI

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !9235