Improved efficiency in COutPoint constructors

src/primitives/transaction.h

@@ -22,8 +22,8 @@ public:
     uint256 hash;
     uint32_t n;
 
-    COutPoint() { SetNull(); }
+    COutPoint(): n((uint32_t) -1) { }
-    COutPoint(uint256 hashIn, uint32_t nIn) { hash = hashIn; n = nIn; }
+    COutPoint(const uint256& hashIn, uint32_t nIn): hash(hashIn), n(nIn) { }
 
     ADD_SERIALIZE_METHODS;