macOS: CMAKE_CROSSCOMPILING not set when building arm64 binaries on a x86_64
When trying to build
arm64 only binaries on a
x86_64 machine, the
CMAKE_CROSSCOMPILING is not set to
Therefore, checking if we are crosscompiling to avoid running macros such as
check_c_source_runs will not work resulting in not setting some variables.
CMakeDetermineSystem.cmake should, on macOS, check current arch as well as if
CMAKE_OSX_ARCHITECTURES is set and determine wether we are cross-compiling or not.