sk-queue: Use int values in getsockopt

The kernel threats them as interger values so
we should declare them this way. Moreover, explicitly
clean them up to eliminate side effects.

Initially I hit a problem where high bits of long "size"
variable was containing some crap from stack and in result
I've got errors like

 | Error (sk-queue.c:102): dump_sk_queue: Can't allocate 171798904800 bytes
 | Error (cr-dump.c:1289): Dump files (pid: 2505) failed with -1

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>