Added comment for rdbms::Login::s_hiddenPassword and made it a constant

rdbms/Login.cpp

@@ -39,7 +39,7 @@ const char *Login::s_fileFormat = "one of "
   "mysql://<username>:<password>@<host>:<port>/<db_name> or "
   "postgresql:[connectinfo | URI]";
 
-std::string Login::s_hiddenPassword = "******";
+const std::string Login::s_hiddenPassword = "******";
 
 const std::string Login::DbTypeAndConnectionDetails::in_memory = "in_memory";
 const std::string Login::DbTypeAndConnectionDetails::oracle = "oracle";

rdbms/Login.hpp

@@ -257,7 +257,10 @@ struct Login {
    */
   static const char *s_fileFormat;
   
-  static std::string s_hiddenPassword;
+  /**
+   * String displayed instead of the actual password.
+   */
+  static const std::string s_hiddenPassword;
   
 private:
   /**