net: add ability to set mtu for devices

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
net: generate a random name for veth device

In a kernel a veth pair is created in a current namespace
and only then a link is moved in a target namespace. So
names of links should be uniq in the current namespace.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
net: add ability to set dev for route nexthop

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
security: don't drop capabilities above last_cap (v2)

prctl(PR_CAPBSET_DROP) returns EINVAL in this case

v2: move linux_get_last_capability() in linux_kernel.c
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Merge some fixes from Andrey