zdtm/socket_aio: add the nouser flag

======================= Run zdtm/static/socket_aio in h ========================
Makefile:295: target 'mnt_enablefs.pid' given more than once in the same rule
Start test
Makefile:295: target 'mnt_enablefs.pid' given more than once in the same rule
./socket_aio --pidfile=socket_aio.pid --outfile=socket_aio.out
Run criu dump
=[log]=> dump/zdtm/static/socket_aio/24/1/dump.log
------------------------ grep Error ------------------------
(00.003450) Error (util.c:665): exited, status=3
(00.009104) Error (util.c:665): exited, status=3
(00.024564) Error (util.c:665): exited, status=3
(00.024598) Error (netfilter.c:88): Iptables configuration failed: Success
(00.024625) Error (cr-dump.c:1297): Dump files (pid: 24) failed with -1
(00.025117) Error (cr-dump.c:1605): Dumping FAILED.
------------------------ ERROR OVER ------------------------
Wait for zdtm/static/socket_aio to die for 0.100000

Reported-by: Mr Jenkins
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/static/socket_aio.desc

-{'opts': '--tcp-established'}
+{'opts': '--tcp-established', 'flags' : 'nouser'}