Get SSL 3.0 server tests working.

The missing SSL 3.0 client support in runner.go was fairly minor.

Change-Id: Ibbd440c9b6be99be08a214dec6b93ca358d8cf0a
Reviewed-on: https://boringssl-review.googlesource.com/1516
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/key_agreement.go b/ssl/test/runner/key_agreement.go
index a678fee..2e2eff4 100644
--- a/ssl/test/runner/key_agreement.go
+++ b/ssl/test/runner/key_agreement.go
@@ -87,10 +87,14 @@
 		return nil, nil, err
 	}
 	ckx := new(clientKeyExchangeMsg)
-	ckx.ciphertext = make([]byte, len(encrypted)+2)
-	ckx.ciphertext[0] = byte(len(encrypted) >> 8)
-	ckx.ciphertext[1] = byte(len(encrypted))
-	copy(ckx.ciphertext[2:], encrypted)
+	if clientHello.vers != VersionSSL30 {
+		ckx.ciphertext = make([]byte, len(encrypted)+2)
+		ckx.ciphertext[0] = byte(len(encrypted) >> 8)
+		ckx.ciphertext[1] = byte(len(encrypted))
+		copy(ckx.ciphertext[2:], encrypted)
+	} else {
+		ckx.ciphertext = encrypted
+	}
 	return preMasterSecret, ckx, nil
 }