message: GCC warning fix
diff: # define ENOKI_UNLIKELY(x) __builtin_expect(!!(x), 0)
  # define ENOKI_PACK __attribute__ ((packed))
  # define ENOKI_MAY_ALIAS __attribute__ ((may_alias))
  +#if defined(__clang__)
  # if !defined(ENOKI_UNROLL)
  # define ENOKI_UNROLL _Pragma("unroll")
  # endif
  # define ENOKI_NOUNROLL _Pragma("nounroll")
  +#else
  +# define ENOKI_UNROLL
  +# define ENOKI_NOUNROLL
  +#endif
  # define ENOKI_IMPORT
  # define ENOKI_EXPORT __attribute__ ((visibility("default")))
  #endif
  