[numerics] fix tlsvar in C++ mode
#ifdef SWIG
#define tlsvar
- #elif defined(SICONOS_CXXVERSION) && (SICONOS_CXXVERSION >= 201103L)
+ #elif __cplusplus >= 201103L
#define tlsvar thread_local
#else
#if defined(__GNUC__) || (defined(__ICC) && defined(__linux))
