gdb: Add circular_buffer.size() and circular_buffer.external_memory_footprint()
gdb: Add circular_buffer.size() and circular_buffer.external_memory_footprint()

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