app: Do not coredump on missing options
app: Do not coredump on missing options

When a seastar::app starts but argv doesn't have mandatary
options, the bpo::notify throws the respective exception and
the program aborts (with core-dump). In particular the iotune
does so.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>
Message-Id: <20200618085935.3823-1-c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>

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