Add double-dash to lxc-netstat re-call arguments

When lxc-netstat was called by lxc-unshare, it would be given the
arguments intended for netstat from the first invocation, but without
anything to separate them from the arguments intended for lxc-netstat.
This meant that netstat arguments like -n would result in lxc-netstat
trying to process them.

Signed-off-by: Andrew Gilbert <andrewg800@gmail.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Add -n differentiation to lxc-netstat

lxc-netstat now only processes an -n argument if it has not previously
received a value for $name from --name or -n. If it _has_ received such
a value, it stops processing arguments and leaves the -n for netstat.
This does not apply to the use of --name after a name has been provided
by --name or -n; the current behaviour continues. The new behaviour
makes
	netstat -n <container> -n -a
behave like
	netstat -n <container> -a -n
which already will act as though there is '--' between '<container>' and
'-a' (see line 91 of lxc-netstat.in).

Signed-off-by: Andrew Gilbert <andrewg800@gmail.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>