Remove support for processing fragmented alerts

Prior to this change, BoringSSL maintained a 2-byte buffer for alerts,
and would support reassembly of fragmented alerts.

NSS does not support fragmented alerts, nor would any reasonable
implementation produce them. Remove fragmented alert handling and
produce an error if a fragmented alert has ever been encountered.

Change-Id: I31530ac372e8a90b47cf89404630c1c207cfb048
Reviewed-on: https://boringssl-review.googlesource.com/2125
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index 6130343..9f79778 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -431,6 +431,13 @@
 	// the first 6 bytes of the ClientHello.
 	FragmentClientVersion bool
 
+	// FragmentAlert will cause all alerts to be fragmented across
+	// two records.
+	FragmentAlert bool
+
+	// SendSpuriousAlert will cause an spurious, unwanted alert to be sent.
+	SendSpuriousAlert bool
+
 	// RsaClientKeyExchangeVersion, if non-zero, causes the client to send a
 	// ClientKeyExchange with the specified version rather than the
 	// client_version when performing the RSA key exchange.