CMake: Enable WASAPI on WinRT WASAPI backend on WinRT was implemented with 2.0.8 https://github.com/libsdl-org/SDL/commit/351d6d478443fe8a1ede1e993712f07cb369d483 but CMake source here was written for 2.0.7 in vcpkg https://github.com/microsoft/vcpkg/commit/e6c65b93b125cf0be13254cf2f5a9d27cb009707