NFS, NIS: abort all tests when we were unable to claim all needed hosts

Signed-off-by: Olaf Kirch <okir@suse.de>
selftest/functions: rewrote the stack handling

Signed-off-by: Olaf Kirch <okir@suse.de>
Added a lot more stuff to nfs suite

Signed-off-by: Olaf Kirch <okir@suse.de>