Fix double-free crash in BSecureSocket when cert. verification fails

* BSecureSocket::CertificateVerificationFailed() took a BCertificate
  instance by value as parameter.
  BCertificate deletes internal data in its destructor. Passing an
  object by value creates a copy, so the copy attempted to delete
  the internal data again during its destruction.
  This caused mail_daemon to crash here when it came across a failed
  certificate.

* Fix: pass BCertificate object as reference.

headers/os/net/SecureSocket.h

@@ -20,7 +20,7 @@ public:
 								BSecureSocket(const BSecureSocket& other);
 	virtual						~BSecureSocket();
 
-	virtual bool				CertificateVerificationFailed(BCertificate);
+	virtual bool				CertificateVerificationFailed(BCertificate&);
 
 	// BSocket implementation
 

src/kits/network/libnetapi/SecureSocket.cpp

@@ -154,7 +154,8 @@ BSecureSocket::Private::VerifyCallback(int ok, X509_STORE_CTX* ctx)
 		return 0;
 
 	// Let the BSecureSocket (or subclass) decide if we should continue anyway.
-	return socket->CertificateVerificationFailed(BCertificate(certificate));
+	BCertificate failedCertificate(certificate);
+	return socket->CertificateVerificationFailed(failedCertificate);
 }
 
 
@@ -285,7 +286,7 @@ BSecureSocket::WaitForReadable(bigtime_t timeout) const
 
 
 bool
-BSecureSocket::CertificateVerificationFailed(BCertificate)
+BSecureSocket::CertificateVerificationFailed(BCertificate&)
 {
 	// Until apps actually make use of the certificate API, let's keep the old
 	// behavior and accept all connections, even if the certificate validation
@@ -357,7 +358,7 @@ BSecureSocket::~BSecureSocket()
 
 
 bool
-BSecureSocket::CertificateVerificationFailed(BCertificate)
+BSecureSocket::CertificateVerificationFailed(BCertificate&)
 {
 	return false;
 }