Add tests for bad CertificateVerify signatures.

I don't think we had coverage for this check.

Change-Id: I5e454e69c1ee9f1b9760d2ef1431170d76f78d63
Reviewed-on: https://boringssl-review.googlesource.com/5544
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index ddd0468..07cb175 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -400,6 +400,10 @@
 	// ServerKeyExchange message should be invalid.
 	InvalidSKXSignature bool
 
+	// InvalidCertVerifySignature specifies that the signature in a
+	// CertificateVerify message should be invalid.
+	InvalidCertVerifySignature bool
+
 	// InvalidSKXCurve causes the curve ID in the ServerKeyExchange message
 	// to be wrong.
 	InvalidSKXCurve bool