crypto, crypto/ecies, crypto/secp256k1: libsecp256k1 scalar mult

thanks to Felix Lange (fjl) for help with design & impl

p2p/rlpx_test.go

@@ -93,6 +93,7 @@ func testEncHandshake(token []byte) error {
 	go func() {
 		r := result{side: "initiator"}
 		defer func() { output <- r }()
+		defer fd0.Close()
 
 		dest := &discover.Node{ID: discover.PubkeyID(&prv1.PublicKey)}
 		r.id, r.err = c0.doEncHandshake(prv0, dest)
@@ -107,6 +108,7 @@ func testEncHandshake(token []byte) error {
 	go func() {
 		r := result{side: "receiver"}
 		defer func() { output <- r }()
+		defer fd1.Close()
 
 		r.id, r.err = c1.doEncHandshake(prv1, nil)
 		if r.err != nil {