temporary_buffer: mark methods noexcept
temporary_buffer: mark methods noexcept

Mark no-throwing methods as noexcept.
We'd like that for marking input_stream methods
that use temporary_buffer noexcept.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

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