Use host_win32 not platform_win32 in kfreebsd defines
Define PLATFORM_GNU which covers any OS with GNU userland.

This define covers kFreeBSD, not just Linux. This is required because
the error which 120d194d10ad351dd95450749cc4a62331331d8a works around is
a GNU problem, not a Linux problem, so causes FTBFS on kFreeBSD.