Add tests for bidirectional shutdown.

Now that it even works at all (type = 0 bug aside), add tests for it.
Test both close_notify being received before and after SSL_shutdown is
called. In the latter case, have the peer send some junk to be ignored
to test that works.

Also test that SSL_shutdown fails on unclean shutdown and that quiet
shutdowns ignore it.

BUG=526437

Change-Id: Iff13b08feb03e82f21ecab0c66d5f85aec256137
Reviewed-on: https://boringssl-review.googlesource.com/5769
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index f841293..2b7e29b 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -753,6 +753,15 @@
 	// ExpectedCustomExtension, if not nil, contains the expected contents
 	// of a custom extension.
 	ExpectedCustomExtension *string
+
+	// NoCloseNotify, if true, causes the close_notify alert to be skipped
+	// on connection shutdown.
+	NoCloseNotify bool
+
+	// ExpectCloseNotify, if true, requires a close_notify from the peer on
+	// shutdown. Records from the peer received after close_notify is sent
+	// are not discard.
+	ExpectCloseNotify bool
 }
 
 func (c *Config) serverInit() {