incremental_reader_selector: use lazy_deref instead of tertiary operator
incremental_reader_selector: use lazy_deref instead of tertiary operator

Signed-off-by: Botond Dénes <a584fa4d75a0a85d721f44fb6e06315a2853b0b6@scylladb.com>
Message-Id: <4f4b884c6a1f517bd654f3b27608d854b17a66e1.1502948635.git.a584fa4d75a0a85d721f44fb6e06315a2853b0b6@scylladb.com>

scylladb/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,duarten/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla,duarten/scylla