Check in the vendor directory

Travis seems to be having issues pulling deps, so we'll have to check in
the vendor directory and prevent the makefile from trying to regenerate
it normally.

vendor/golang.org/x/sys/unix/dirent.go

@@ -0,0 +1,17 @@
+// Copyright 2009 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 darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package unix
+
+import "syscall"
+
+// ParseDirent parses up to max directory entries in buf,
+// appending the names to names. It returns the number of
+// bytes consumed from buf, the number of entries added
+// to names, and the new names slice.
+func ParseDirent(buf []byte, max int, names []string) (consumed int, count int, newnames []string) {
+	return syscall.ParseDirent(buf, max, names)
+}