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/chainparamsbase.h

@@ -55,4 +55,4 @@ bool SelectBaseParamsFromCommandLine();
  */
 bool AreBaseParamsConfigured();
 
-#endif
+#endif // BITCOIN_CHAIN_PARAMS_BASE_H