test/vfork00: mark vfork test as expected to fail

We don't have a way to dump proccess blocked in vfork(), hence
mark this test as expected to fail.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/static/vfork00.desc

-{'flags': 'noauto'}
+{'flags': 'noauto crfail'}