tls: fix references to undefined cb

5795e83 introduced unintentional
copy-paste bug. `cb` is not actually present in those functions and
should not be called, the socket should be destroy instead.

PR-URL: #1951
Reviewed-By: Roman Reiss <me@silverwind.io>

lib/_tls_wrap.js

@@ -167,7 +167,7 @@ function oncertcb(info) {
         return self.destroy(err);
 
       if (!self._handle)
-        return cb(new Error('Socket is closed'));
+        return self.destroy(new Error('Socket is closed'));
 
       self._handle.certCbDone();
     });
@@ -192,7 +192,7 @@ function onnewsession(key, session) {
     once = true;
 
     if (!self._handle)
-      return cb(new Error('Socket is closed'));
+      return self.destroy(new Error('Socket is closed'));
 
     self._handle.newSessionDone();