Macros for C++ version compatibility.
// option 1: when the library is linked using cmake
#ifdef KANI_INCLUDED_MACROS_HPP
#include <kani/macros.hpp>
// option 2: otherwise, copy the necessary macros from kani/macros.hpp
#else
#define KANI_CXX_VER ...
#define KANI_CXX11 201103L
#define KANI_CXX14 201402L
#endif
void func() {
if (KANI_CXX_VER == KANI_CXX11) { ... }
}