Return generic key from TlsKeyOpenSSL::handle

We already return RSA/DSA/DH/EC, so we can also return generic.

Fixes: QTBUG-115718
Change-Id: I2064c2bbce2df73985609d27a94857a0ee2e6b42
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/plugins/tls/openssl/qtlskey_openssl.cpp

@@ -222,7 +222,7 @@ Qt::HANDLE TlsKeyOpenSSL::handle() const
 #else
     qCWarning(lcTlsBackend,
               "This version of OpenSSL disabled direct manipulation with RSA/DSA/DH/EC_KEY structures, consider using QSsl::Opaque instead.");
-    return Qt::HANDLE(nullptr);
+    return Qt::HANDLE(genericKey);
 #endif
 }