sentry: Get "ip link" working.
sentry: Get "ip link" working.

In Linux, many UDS ioctls are passed through to the NIC driver. We do the same
here, passing ioctl calls to Unix sockets through to epsocket.

In Linux you can see this path at net/socket.c:sock_ioctl, which calls
sock_do_ioctl, which calls net/core/dev_ioctl.c:dev_ioctl.

SIOCGIFNAME is also added.

PiperOrigin-RevId: 197167508
Change-Id: I62c326a4792bd0a473e9c9108aafb6a6354f2b64

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor