crypto: make receiver name consistent

Fixes go lint warning.

Change-Id: I63950e7c70bf431e88a04f32befd50be9beacadf
Reviewed-on: https://go-review.googlesource.com/108815Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/crypto/sha1/sha1.go

@@ -150,10 +150,10 @@ func (d *digest) Write(p []byte) (nn int, err error) {
 	return
 }
 
-func (d0 *digest) Sum(in []byte) []byte {
-	// Make a copy of d0 so that caller can keep writing and summing.
-	d := *d0
-	hash := d.checkSum()
+func (d *digest) Sum(in []byte) []byte {
+	// Make a copy of d so that caller can keep writing and summing.
+	d0 := *d
+	hash := d0.checkSum()
 	return append(in, hash[:]...)
 }
 
@@ -189,9 +189,9 @@ func (d *digest) checkSum() [Size]byte {
 }
 
 // ConstantTimeSum computes the same result of Sum() but in constant time
-func (d0 *digest) ConstantTimeSum(in []byte) []byte {
-	d := *d0
-	hash := d.constSum()
+func (d *digest) ConstantTimeSum(in []byte) []byte {
+	d0 := *d
+	hash := d0.constSum()
 	return append(in, hash[:]...)
 }
 

src/crypto/sha256/sha256.go

@@ -223,11 +223,11 @@ func (d *digest) Write(p []byte) (nn int, err error) {
 	return
 }
 
-func (d0 *digest) Sum(in []byte) []byte {
-	// Make a copy of d0 so that caller can keep writing and summing.
-	d := *d0
-	hash := d.checkSum()
-	if d.is224 {
+func (d *digest) Sum(in []byte) []byte {
+	// Make a copy of d so that caller can keep writing and summing.
+	d0 := *d
+	hash := d0.checkSum()
+	if d0.is224 {
 		return append(in, hash[:Size224]...)
 	}
 	return append(in, hash[:]...)

src/crypto/sha512/sha512.go

@@ -286,12 +286,12 @@ func (d *digest) Write(p []byte) (nn int, err error) {
 	return
 }
 
-func (d0 *digest) Sum(in []byte) []byte {
-	// Make a copy of d0 so that caller can keep writing and summing.
-	d := new(digest)
-	*d = *d0
-	hash := d.checkSum()
-	switch d.function {
+func (d *digest) Sum(in []byte) []byte {
+	// Make a copy of d so that caller can keep writing and summing.
+	d0 := new(digest)
+	*d0 = *d
+	hash := d0.checkSum()
+	switch d0.function {
 	case crypto.SHA384:
 		return append(in, hash[:Size384]...)
 	case crypto.SHA512_224: