MOVEONLY: CBlockUndo from main.h to undo.h

src/undo.h

@@ -68,4 +68,18 @@ public:
     }
 };
 
+/** Undo information for a CBlock */
+class CBlockUndo
+{
+public:
+    std::vector<CTxUndo> vtxundo; // for all but the coinbase
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(vtxundo);
+    }
+};
+
 #endif // BITCOIN_UNDO_H