future: specify uninitialized_wrapper_base default constructors as noexcept
future: specify uninitialized_wrapper_base default constructors as noexcept

Also future_state and future_state_base default constructors can just be declared as default.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>
Message-Id: <20200525151658.329320-1-23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

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