Update golang.org/x/crypto/scrypt

vendor/manifest

@@ -66,8 +66,8 @@
 		{
 			"importpath": "golang.org/x/crypto/scrypt",
 			"repository": "https://go.googlesource.com/crypto",
-			"revision": "cc04154d65fb9296747569b107cfd05380b1ea3e",
-			"branch": "HEAD",
+			"revision": "81372b2fc2f10bef2a7f338da115c315a56b2726",
+			"branch": "master",
 			"path": "/scrypt"
 		},
 		{

vendor/src/golang.org/x/crypto/scrypt/scrypt.go

@@ -218,7 +218,7 @@ func smix(b []byte, r, N int, v, xy []uint32) {
 // For example, you can get a derived key for e.g. AES-256 (which needs a
 // 32-byte key) by doing:
 //
-//      dk := scrypt.Key([]byte("some password"), salt, 16384, 8, 1, 32)
+//      dk, err := scrypt.Key([]byte("some password"), salt, 16384, 8, 1, 32)
 //
 // The recommended parameters for interactive logins as of 2009 are N=16384,
 // r=8, p=1. They should be increased as memory latency and CPU parallelism