net: Don't use variable length arrays
net: Don't use variable length arrays

-Wstack-usage warns on them and in this case it was not even saving an
allocation

This is a new version of 255ba91df684295d5745b4eb38326f1f4742876a
which also works with c++14.

Signed-off-by: Rafael Ávila de Espíndola <1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>
Message-Id: <20200127011623.21362-1-1975039f9046bf513b77c0c5639a0efc25f00e7f@scylladb.com>

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