fix incorrect factoring

tinyxml2.cpp

@@ -809,12 +809,12 @@ void XMLNode::Unlink( XMLNode* child )
 
     if ( child->_prev ) {
         child->_prev->_next = child->_next;
-        child->_prev = 0;
     }
     if ( child->_next ) {
         child->_next->_prev = child->_prev;
-        child->_next = 0;
     }
+	child->_next = 0;
+	child->_prev = 0;
 	child->_parent = 0;
 }