portlist: add a lint ignore for unused function.

The function is indeed unused on linux, but we want it around
so that unit tests exercise the netstat logic even on linux,
even if it's only used on !linux.

Signed-off-by: David Anderson <dave@natulte.net>

portlist/netstat.go

@@ -132,6 +132,8 @@ func parsePortsNetstat(output string) List {
 	return l
 }
 
+//lint:ignore U1000 function is only used on !linux, but we want the
+// unit test to run on linux, so we don't build-tag it away.
 func listPortsNetstat(args string) (List, error) {
 	exe, err := exec.LookPath("netstat")
 	if err != nil {