posix: Add a few no-op file functions to unistd
posix: Add a few no-op file functions to unistd

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