parasite: Don't recreate host-side transport socket
parasite: Don't recreate host-side transport socket

When dumping a net namespace we'll have to create the transport
socket in the target namespace. In order to do this we'll have
to call setns swice -- before and after socket() call.

I don't want to do it for every single task to dump, let's cache
the socket instead.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

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