Regression test for CVE-2015-0291.

This is really just scar tissue with https://crbug.com/468889 being the real
underlying problem. But the test is pretty easy.

Change-Id: I5eca18fdcbde8665c0e6c3ac419a28152647d66f
Reviewed-on: https://boringssl-review.googlesource.com/4052
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index a33ad19..5cad289 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -667,6 +667,10 @@
 	// NeverResumeOnRenego, if true, causes renegotiations to always be full
 	// handshakes.
 	NeverResumeOnRenego bool
+
+	// NoSignatureAlgorithmsOnRenego, if true, causes renegotiations to omit
+	// the signature_algorithms extension.
+	NoSignatureAlgorithmsOnRenego bool
 }
 
 func (c *Config) serverInit() {