C# is broken on Windows x86

Something is amiss with C# on x86. %csexposefun seems to not need SWIGSTDCALL as that causes calling convention incompatibility and thus crashes on x86. Fixing that alone is not enough, something else causes a different but potentially related crash (esp register gets corrupted). For now C# tests on x86 are disabled, reenable them in build.yml when this gets fixed.