Since NetBSD does not support uname -o, push check for CygWin inside separate non-failing condition in Makefile. Change-Id: Ibd264384f49b33412f0ef8554bd9c9fb8f60a892 Signed-off-by: Andrey Korolyov <andrey@xdel.ru> Reviewed-on: https://review.coreboot.org/12831 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi <pgeorgi@google.com>