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/hash.h

@@ -159,4 +159,4 @@ uint256 SerializeHash(const T& obj, int nType=SER_GETHASH, int nVersion=PROTOCOL
 
 unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char>& vDataToHash);
 
-#endif
+#endif // BITCOIN_HASH_H