test: add OS::total_memuse() and memory_end_ to os_mock
test: add OS::total_memuse() and memory_end_ to os_mock

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