Guard against passing undefined C2SPid to xml parser before become_controller gets called

Our new nif xml parser don't handle this gracefully, so we better don't
call it that way.

This is only triggered on old style ssl sockets, where ssl layer must
be activated early, before association between socket and c2s is
established

src/ejabberd_receiver.erl

@@ -159,8 +159,13 @@ handle_call({starttls, TLSSocket}, _From,
 		   c2s_pid = C2SPid,
 		   max_stanza_size = MaxStanzaSize} = State) ->
     close_stream(XMLStreamState),
-    NewXMLStreamState = xml_stream:new(C2SPid,
-				       MaxStanzaSize),
+    NewXMLStreamState = case C2SPid of
+                            undefined ->
+                                XMLStreamState;
+                            _ ->
+                                xml_stream:new(C2SPid,
+                                               MaxStanzaSize)
+                        end,
     NewState = State#state{socket = TLSSocket,
 			   sock_mod = p1_tls,
 			   xml_stream_state = NewXMLStreamState},
@@ -347,7 +352,12 @@ process_data(Data,
 		    shaper_state = ShaperState, c2s_pid = C2SPid} =
 		 State) ->
     ?DEBUG("Received XML on stream = ~p", [(Data)]),
-    XMLStreamState1 = xml_stream:parse(XMLStreamState, Data),
+    XMLStreamState1 = case XMLStreamState of
+                          undefined ->
+                              XMLStreamState;
+                          _ ->
+                              xml_stream:parse(XMLStreamState, Data)
+                      end,
     {NewShaperState, Pause} = shaper:update(ShaperState, byte_size(Data)),
     if
 	C2SPid == undefined ->