Add a packed renegotiation test.

Ridiculous as it is, the protocol does not forbid packing HelloRequest
and Finished into the same record. Add a test for this case.

Change-Id: I8e1455b261f56169309070bf44d14d40a63eae50
Reviewed-on: https://boringssl-review.googlesource.com/8901
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/test/runner/conn.go b/ssl/test/runner/conn.go
index fbd501a..1b6c557 100644
--- a/ssl/test/runner/conn.go
+++ b/ssl/test/runner/conn.go
@@ -1268,6 +1268,10 @@
 	c.out.Lock()
 	defer c.out.Unlock()
 
+	// Flush any pending handshake data. PackHelloRequestWithFinished may
+	// have been set and the handshake not followed by Renegotiate.
+	c.flushHandshake()
+
 	if err := c.out.err; err != nil {
 		return 0, err
 	}