Bump cfssl to be compatible with Go 1.10

vendor/github.com/google/certificate-transparency-go/x509/root_linux.go

@@ -0,0 +1,14 @@
+// Copyright 2015 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.
+
+package x509
+
+// Possible certificate files; stop after finding one.
+var certFiles = []string{
+	"/etc/ssl/certs/ca-certificates.crt",                // Debian/Ubuntu/Gentoo etc.
+	"/etc/pki/tls/certs/ca-bundle.crt",                  // Fedora/RHEL 6
+	"/etc/ssl/ca-bundle.pem",                            // OpenSUSE
+	"/etc/pki/tls/cacert.pem",                           // OpenELEC
+	"/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem", // CentOS/RHEL 7
+}