add missing header end comments

- ensures a consistent usage in header files
- also add a blank line after the copyright header where missing
- also remove orphan new-lines at the end of some files

src/txmempool.h

@@ -2,6 +2,7 @@
 // Copyright (c) 2009-2013 The Bitcoin developers
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
 #ifndef BITCOIN_TXMEMPOOL_H
 #define BITCOIN_TXMEMPOOL_H
 
@@ -147,4 +148,4 @@ public:
     bool HaveCoins(const uint256 &txid) const;
 };
 
-#endif /* BITCOIN_TXMEMPOOL_H */
+#endif // BITCOIN_TXMEMPOOL_H