future: future_state: mark set as noexcept
future: future_state: mark set as noexcept

It constructs the future_state in place using
a non-throwing constructor and std::forwarding
the arguments.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>
Message-Id: <20200617163407.564579-1-23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

dreamsxin/seastar,cloudius-systems/seastar,dreamsxin/seastar,dreamsxin/seastar,avikivity/seastar,syuu1228/seastar,scylladb/seastar,cloudius-systems/seastar,syuu1228/seastar,avikivity/seastar,scylladb/seastar,avikivity/seastar,syuu1228/seastar,cloudius-systems/seastar,scylladb/seastar