compound: fix compare() of prefixable types
compound: fix compare() of prefixable types

All components of prefixable compound type are preceeded by their
length what makes them not byte order comparable.

Signed-off-by: Paweł Dziepak <e29bb3265626c60caf76d587cabdfcd8b379ef80@scylladb.com>

raphaelsc/scylla,avikivity/scylla,avikivity/scylla,raphaelsc/scylla,kjniemi/scylla,scylladb/scylla,scylladb/scylla,kjniemi/scylla,kjniemi/scylla,duarten/scylla,avikivity/scylla,raphaelsc/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,duarten/scylla