Cleanup: Don't check for negative values from EVP_DigestVerifyFinal.

crypto/signature_verifier_openssl.cc

Index: crypto/signature_verifier_openssl.cc
diff --git a/crypto/signature_verifier_openssl.cc b/crypto/signature_verifier_openssl.cc
index 53637ebb60a269eb90f34e69e57d847498a3eef8..84aa2ea3912017178120df4bc9ee52354edd284f 100644
--- a/crypto/signature_verifier_openssl.cc
+++ b/crypto/signature_verifier_openssl.cc
@@ -122,8 +122,7 @@ bool SignatureVerifier::VerifyFinal() {
   int rv = EVP_DigestVerifyFinal(verify_context_->ctx.get(),
                                  vector_as_array(&signature_),
                                  signature_.size());
-  // rv is -1 if a DER-encoded ECDSA signature cannot be decoded correctly.
-  DCHECK_GE(rv, -1);
+  DCHECK_EQ(!!rv, rv);
   Reset();
   return rv == 1;
 }