Don't deref v if it's NULL.

Klocwork #214
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 640b70f..0b853b5 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -2493,8 +2493,10 @@
 	}
 
 	v = Tktt_New(func);
-	v->token = Tcl_CreateTimerHandler(milliseconds, TimerHandler,
-					  (ClientData)v);
+	if (v) {
+		v->token = Tcl_CreateTimerHandler(milliseconds, TimerHandler,
+						  (ClientData)v);
+	}
 
 	return (PyObject *) v;
 }