enable v8plus_call to be used in any thread

@@ -27,13 +27,10 @@
 
 #if NODE_MINOR_VERSION > 7 || NODE_MAJOR_VERSION > 0
 #define NODE_MAKECALLBACK_RETURN
 #endif
 
-extern "C" boolean_t v8plus_in_event_thread(void);
-extern "C" void v8plus_crossthread_init(void);
-
 namespace v8plus {
 
 class ObjectWrap;
 
 class ObjectWrap : public node::ObjectWrap {