Decouple CCoins from CTxInUndo

src/coins.h

@@ -9,7 +9,6 @@
 #include "compressor.h"
 #include "serialize.h"
 #include "uint256.h"
-#include "undo.h"
 
 #include <assert.h>
 #include <stdint.h>
@@ -237,11 +236,8 @@ public:
         Cleanup();
     }
 
-    //! mark an outpoint spent, and construct undo information
-    bool Spend(const COutPoint &out, CTxInUndo &undo);
-
     //! mark a vout spent
-    bool Spend(int nPos);
+    bool Spend(uint32_t nPos);
 
     //! check whether a particular output is still available
     bool IsAvailable(unsigned int nPos) const {