travis-test: select tests skipped by lazy-pages pass more carefully

Most of zdtm test should pass with --lazy-pages with kernels newer than
4.11.
Some test excluded for older kernels surprisingly pass even now, mainly
becuase they do not actually stress userfaultfd, which will be fixed in the
upcoming commits :)
The cmdlinenv00 fails even with kernel 4.11 because of a race between uffd
and gup in the case external process reads /proc/<pid>/cmdline before
memory containing the command line is populated.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>