add config.SkipErrorENOBUFS option

[patryk4815]

Im just upstreaming patches that I had on my company hardfork since 5years.
When I have a lot of messages on netlink, I may get an ENOBUFS error, which causes netlink to close its socket.
This NoENOBUFS option causes the socket to continue working, but will lose some of the messages.

Some more info about ENOBUFS: google/nftables#103

[florianl]

Thanks for your contribution and bringing this topic back upstream.
Instead of harcording this single option providing a proper API to set all available netlink.ConnOption should be prefered.

// SetOption allows to enable or disable netlink socket options.
func (nflog *Nflog) SetOption(o netlink.ConnOption, enable bool) error

Would you be interested in contributing this?

[florianl]

Superseded by #40.