scylla-gdb.py: Make intrusive_list() work with newer version of boost
scylla-gdb.py: Make intrusive_list() work with newer version of boost

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