The kernel support for lazy pages (userfaultfd) lacks many important
features which effectively prevents success in certain tests.
Allow skipping such test with somewhat informative message

travis-ci: success for lazy-pages: improve testability (rev2)
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>