posix: Check for null in open() before everyhing else
posix: Check for null in open() before everyhing else

hioa-cs/IncludeOS,mnordsletten/IncludeOS,alfred-bratterud/IncludeOS,mnordsletten/IncludeOS,mnordsletten/IncludeOS,hioa-cs/IncludeOS,alfred-bratterud/IncludeOS,AnnikaH/IncludeOS,ingve/IncludeOS,mnordsletten/IncludeOS,AndreasAakesson/IncludeOS,AndreasAakesson/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,hioa-cs/IncludeOS,AndreasAakesson/IncludeOS,alfred-bratterud/IncludeOS,alfred-bratterud/IncludeOS,ingve/IncludeOS,hioa-cs/IncludeOS,mnordsletten/IncludeOS,hioa-cs/IncludeOS,AnnikaH/IncludeOS,ingve/IncludeOS,AndreasAakesson/IncludeOS,AndreasAakesson/IncludeOS,AnnikaH/IncludeOS,alfred-bratterud/IncludeOS,AnnikaH/IncludeOS,ingve/IncludeOS,mnordsletten/IncludeOS,ingve/IncludeOS