Silence clang-cl -Wdeprecated warning

warning: definition of implicit copy constructor for 'error' is deprecated because it has a user-declared destructor [-Wdeprecated]

calculator.hpp

@@ -7,7 +7,7 @@
 /// @author    Kim Walisch, <[email protected]>
 /// @copyright Copyright (C) 2013-2018 Kim Walisch
 /// @license   BSD 2-Clause, https://opensource.org/licenses/BSD-2-Clause
-/// @version   1.3
+/// @version   1.4
 ///
 /// == Supported operators ==
 ///
@@ -80,10 +80,7 @@ class error : public std::runtime_error
     : std::runtime_error(message),
       expr_(expr)
   { }
-#if __cplusplus >= 201103L || \
-    (defined(_MSC_VER) && _MSC_VER >= 1800)
-  ~error() { }
-#else
+#if __cplusplus < 201103L
   ~error() throw() { }
 #endif
   std::string expression() const