Add self-contained gometalinter build tooling.

tools/vendor/github.com/mvdan/unparam/main.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2017, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/mvdan/unparam/check"
+)
+
+var tests = flag.Bool("tests", true, "include tests")
+
+func main() {
+	flag.Parse()
+	warns, err := check.UnusedParams(*tests, flag.Args()...)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	for _, warn := range warns {
+		fmt.Println(warn)
+	}
+}