don't include system headers in dependency files System library headers are not strictly part of our build. If they are changing beneath our feet, then we probably have bigger problems. Signed-off-by: Brian Norris <computersforpeace@gmail.com> Suggested-by: Mike Frysinger <vapier@gentoo.org> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Brian Norris <computersforpeace@gmail.com>