Better document possible results of CMAKE_HOST_SYSTEM_NAME
The docs here:
https://cmake.org/cmake/help/latest/variable/CMAKE_HOST_SYSTEM_NAME.html
only say "Name of the OS CMake is running on.
On systems that have the uname command, this variable is set to the output of uname -s. Linux, Windows, and Darwin for macOS are the values found on the big three operating systems."
Would be nice to state explicitly:
- what about iOS, tvOS, and variants? Did they count as Darwin?
- does Android count as linux?
- what about the BSDs?