message: check stdlib version when deciding whether to use aligned new
diff: @@ -469,12 +469,18 @@ namespace ranges
  #endif
  #endif // RANGES_CXX_IF_CONSTEXPR
  +// Its not enough for the compiler to support this; the stdlib must support it too.
  #ifndef RANGES_CXX_ALIGNED_NEW
  -#ifdef __cpp_aligned_new
  +#if (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION >= 4000) && \
  + (!defined(__GLIBCXX__) || (defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE >= 7))
  +#if defined(__cpp_aligned_new)
  #define RANGES_CXX_ALIGNED_NEW __cpp_aligned_new
  #else
  #define RANGES_CXX_ALIGNED_NEW RANGES_CXX_FEATURE(ALIGNED_NEW)
  #endif
  +#else // _LIBCPP_VERSION < 4000 || __GLIBCXX__ < 20170502
  +#define RANGES_CXX_ALIGNED_NEW 0L
  +#endif
  #endif // RANGES_CXX_ALIGNED_NEW
  #ifdef RANGES_FEWER_WARNINGS
  