basic_sstring: resize uses sstring
basic_sstring: resize uses sstring

Should of course use the template type basic_sstring.

Message-Id: <d375a20c879575d53e5983edafb6f11f4de6c91a@scylladb.com>

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