net/http: remove unused named return variables

The existing implementation names a c net.Conn return which is
never user. Leaving the returns unamed is marginally clearer.

Change-Id: If9a411c9235b78c116a8ffb21fef71f7a4a4ce8f
Reviewed-on: https://go-review.googlesource.com/66890
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/server.go

@@ -3161,10 +3161,10 @@ type tcpKeepAliveListener struct {
 	*net.TCPListener
 }
 
-func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
+func (ln tcpKeepAliveListener) Accept() (net.Conn, error) {
 	tc, err := ln.AcceptTCP()
 	if err != nil {
-		return
+		return nil, err
 	}
 	tc.SetKeepAlive(true)
 	tc.SetKeepAlivePeriod(3 * time.Minute)