Implement HelloRetryRequest in Go.

Change-Id: Ibde837040d2332bc8570589ba5be9b32e774bfcf
Reviewed-on: https://boringssl-review.googlesource.com/8811
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/test/runner/conn.go b/ssl/test/runner/conn.go
index a9e9231..3789b28 100644
--- a/ssl/test/runner/conn.go
+++ b/ssl/test/runner/conn.go
@@ -1137,6 +1137,8 @@
 		m = &serverHelloMsg{
 			isDTLS: c.isDTLS,
 		}
+	case typeHelloRetryRequest:
+		m = new(helloRetryRequestMsg)
 	case typeNewSessionTicket:
 		m = new(newSessionTicketMsg)
 	case typeEncryptedExtensions: