Allocation overriding on Windows with CMake

[seanmiddleditch]

The file alloc-override-win.c is never included or built on Windows when using CMake. It appears that the file is only referenced at all in the provided .vcxproj files, which are not of help to parent CMake projects that are building via add_subdirectory (and may not even be using MSBuild anyway but rather Ninja, which is also the default CMake build system in Visual Studio itself these days).

[daanx]

Ah yes. I never used cmake yet to build on windows but always use the Visual Studio solution. We need to add some rules to build this correctly on Windows.