Don't use __builtin_unreachable on GCC < 4.5.
# else
# if defined(HEDLEY_ASSUME)
# define simde_assert(expr) HEDLEY_ASSUME(expr)
-# elif defined(__GNUC__)
+# elif HEDLEY_GCC_VERSION_CHECK(4,5,0)
# define simde_assert(expr) ((void) (!!(expr) ? 1 : (__builtin_unreachable(), 1)))
-# elif defined(_MSC_VER)
+# elif HEDLEY_MSVC_VERSION_CHECK(13,10,0)
# define simde_assert(expr) __assume(expr)
# else
# define simde_assert(expr)
