stop_iteration: add && and || operators
stop_iteration: add && and || operators

stop_iteration is a type safe bool and it is convenient to have bool-like
operations defined without the need of endless casts.

Signed-off-by: Paweł Dziepak <e29bb3265626c60caf76d587cabdfcd8b379ef80@scylladb.com>
Message-Id: <20161129135031.24484-1-e29bb3265626c60caf76d587cabdfcd8b379ef80@scylladb.com>

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