13b88c21d0
Make std::future a re-export of core::future After 1a764a7ef59b9cb2eb31658625a6a7dacc3d819b, there are no `std::future`-specific items (except for `cfg(bootstrap)` items removed in 93eed402adbe9e7a532995500d50716d52eefee9). So, instead of defining `std` own module, we can re-export the `core::future` directly.