diff --git a/vendor/golang.org/x/sys/unix/mksysnum.go b/vendor/golang.org/x/sys/unix/mksysnum.go
new file mode 100644
index 0000000..07f8960
--- /dev/null
+++ b/vendor/golang.org/x/sys/unix/mksysnum.go
@@ -0,0 +1,190 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+// Generate system call table for DragonFly, NetBSD,
+// FreeBSD, OpenBSD or Darwin from master list
+// (for example, /usr/src/sys/kern/syscalls.master or
+// sys/syscall.h).
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"regexp"
+	"strings"
+)
+
+var (
+	goos, goarch string
+)
+
+// cmdLine returns this programs's commandline arguments
+func cmdLine() string {
+	return "go run mksysnum.go " + strings.Join(os.Args[1:], " ")
+}
+
+// buildTags returns build tags
+func buildTags() string {
+	return fmt.Sprintf("%s,%s", goarch, goos)
+}
+
+func checkErr(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		os.Exit(1)
+	}
+}
+
+// source string and substring slice for regexp
+type re struct {
+	str string   // source string
+	sub []string // matched sub-string
+}
+
+// Match performs regular expression match
+func (r *re) Match(exp string) bool {
+	r.sub = regexp.MustCompile(exp).FindStringSubmatch(r.str)
+	if r.sub != nil {
+		return true
+	}
+	return false
+}
+
+// fetchFile fetches a text file from URL
+func fetchFile(URL string) io.Reader {
+	resp, err := http.Get(URL)
+	checkErr(err)
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	checkErr(err)
+	return strings.NewReader(string(body))
+}
+
+// readFile reads a text file from path
+func readFile(path string) io.Reader {
+	file, err := os.Open(os.Args[1])
+	checkErr(err)
+	return file
+}
+
+func format(name, num, proto string) string {
+	name = strings.ToUpper(name)
+	// There are multiple entries for enosys and nosys, so comment them out.
+	nm := re{str: name}
+	if nm.Match(`^SYS_E?NOSYS$`) {
+		name = fmt.Sprintf("// %s", name)
+	}
+	if name == `SYS_SYS_EXIT` {
+		name = `SYS_EXIT`
+	}
+	return fmt.Sprintf("	%s = %s;  // %s\n", name, num, proto)
+}
+
+func main() {
+	// Get the OS (using GOOS_TARGET if it exist)
+	goos = os.Getenv("GOOS_TARGET")
+	if goos == "" {
+		goos = os.Getenv("GOOS")
+	}
+	// Get the architecture (using GOARCH_TARGET if it exists)
+	goarch = os.Getenv("GOARCH_TARGET")
+	if goarch == "" {
+		goarch = os.Getenv("GOARCH")
+	}
+	// Check if GOOS and GOARCH environment variables are defined
+	if goarch == "" || goos == "" {
+		fmt.Fprintf(os.Stderr, "GOARCH or GOOS not defined in environment\n")
+		os.Exit(1)
+	}
+
+	file := strings.TrimSpace(os.Args[1])
+	var syscalls io.Reader
+	if strings.HasPrefix(file, "https://") || strings.HasPrefix(file, "http://") {
+		// Download syscalls.master file
+		syscalls = fetchFile(file)
+	} else {
+		syscalls = readFile(file)
+	}
+
+	var text, line string
+	s := bufio.NewScanner(syscalls)
+	for s.Scan() {
+		t := re{str: line}
+		if t.Match(`^(.*)\\$`) {
+			// Handle continuation
+			line = t.sub[1]
+			line += strings.TrimLeft(s.Text(), " \t")
+		} else {
+			// New line
+			line = s.Text()
+		}
+		t = re{str: line}
+		if t.Match(`\\$`) {
+			continue
+		}
+		t = re{str: line}
+
+		switch goos {
+		case "dragonfly":
+			if t.Match(`^([0-9]+)\s+STD\s+({ \S+\s+(\w+).*)$`) {
+				num, proto := t.sub[1], t.sub[2]
+				name := fmt.Sprintf("SYS_%s", t.sub[3])
+				text += format(name, num, proto)
+			}
+		case "freebsd":
+			if t.Match(`^([0-9]+)\s+\S+\s+(?:NO)?STD\s+({ \S+\s+(\w+).*)$`) {
+				num, proto := t.sub[1], t.sub[2]
+				name := fmt.Sprintf("SYS_%s", t.sub[3])
+				text += format(name, num, proto)
+			}
+		case "openbsd":
+			if t.Match(`^([0-9]+)\s+STD\s+(NOLOCK\s+)?({ \S+\s+\*?(\w+).*)$`) {
+				num, proto, name := t.sub[1], t.sub[3], t.sub[4]
+				text += format(name, num, proto)
+			}
+		case "netbsd":
+			if t.Match(`^([0-9]+)\s+((STD)|(NOERR))\s+(RUMP\s+)?({\s+\S+\s*\*?\s*\|(\S+)\|(\S*)\|(\w+).*\s+})(\s+(\S+))?$`) {
+				num, proto, compat := t.sub[1], t.sub[6], t.sub[8]
+				name := t.sub[7] + "_" + t.sub[9]
+				if t.sub[11] != "" {
+					name = t.sub[7] + "_" + t.sub[11]
+				}
+				name = strings.ToUpper(name)
+				if compat == "" || compat == "13" || compat == "30" || compat == "50" {
+					text += fmt.Sprintf("	%s = %s;  // %s\n", name, num, proto)
+				}
+			}
+		case "darwin":
+			if t.Match(`^#define\s+SYS_(\w+)\s+([0-9]+)`) {
+				name, num := t.sub[1], t.sub[2]
+				name = strings.ToUpper(name)
+				text += fmt.Sprintf("	SYS_%s = %s;\n", name, num)
+			}
+		default:
+			fmt.Fprintf(os.Stderr, "unrecognized GOOS=%s\n", goos)
+			os.Exit(1)
+
+		}
+	}
+	err := s.Err()
+	checkErr(err)
+
+	fmt.Printf(template, cmdLine(), buildTags(), text)
+}
+
+const template = `// %s
+// Code generated by the command above; see README.md. DO NOT EDIT.
+
+// +build %s
+
+package unix
+
+const(
+%s)`