package pfring incapacitates 'gopls'

My development ubuntu machine does not have the pfring (https://www.ntop.org/guides/pf_ring/index.html ) installed. Without this, VSCode's gopls is unusable.

I'm not using pfring myself, so in my local branch I removed references to pfring and now gopls is happy.

Perhaps adding a separate go.mod in the pfring/ and examples/pfdump/ directory might also fix the problem?

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I assume the problem is with the gopls backend, and not VSCode specific.