ProjectExplorer: Fix compile with MSVC2015

Change-Id: Ia33afa96ff9d5bfc7b0c7020908c5a27274f23ee
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/projectnodes.h

@@ -163,6 +163,7 @@ public:
 protected:
     Node();
     Node(const Node &other) = delete;
+    bool operator=(const Node &other) = delete;
 
     void setNodeType(NodeType nodeType);
     void setFilePath(const Utils::FileName &filePath);