Update to new version of datadog-agent/pkg/ebpf

[drewrip]

kube-netc has been using a fork of datadog/datadog-agent's ebpf library because of some mismatched functions that hadn't been committed upstream to iovisor/gobpf. Their ebpf library does work with their fork datadog/gobpf. Some changes are now needed to fix a bug with ebpf:

2020/06/04 21:27:27 [2020-06-04 21:27:27.10331117 +0000 UTC m=+0.023524112] error: could not enable kprobe(kprobe/tcp_get_info) used for offset guessing: cannot write "p:ptcp_get_info tcp_get_info\n" to kprobe_events: write /sys/kernel/debug/tracing/kprobe_events: file exists

This issue is referenced. I need to bring my fork up to date to fix these changes until their gobpf fork is merged upstream.

[drewrip]

Rather than using a replace to point iovisor/gobpf => DataDog/gobpf, it looks like datadog-agent is going to need to be forked again due to golang/go#26904, a pretty fundamental problem with Go dependency management that disallows aliasing with a fork.

[drewrip]

With some replaces in our go.mod file we now use DataDog/datadog-agent rather than my fork that removed the uncommited code.

#6
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