/usr/include/postgres-xc/server/storage/ is in postgres-xc-server-dev 1.1-2ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/postgres-xc/server/storage/backendid.h
/usr/include/postgres-xc/server/storage/barrier.h
/usr/include/postgres-xc/server/storage/block.h
/usr/include/postgres-xc/server/storage/buf.h
/usr/include/postgres-xc/server/storage/buf_internals.h
/usr/include/postgres-xc/server/storage/buffile.h
/usr/include/postgres-xc/server/storage/bufmgr.h
/usr/include/postgres-xc/server/storage/bufpage.h
/usr/include/postgres-xc/server/storage/copydir.h
/usr/include/postgres-xc/server/storage/fd.h
/usr/include/postgres-xc/server/storage/freespace.h
/usr/include/postgres-xc/server/storage/fsm_internals.h
/usr/include/postgres-xc/server/storage/indexfsm.h
/usr/include/postgres-xc/server/storage/ipc.h
/usr/include/postgres-xc/server/storage/item.h
/usr/include/postgres-xc/server/storage/itemid.h
/usr/include/postgres-xc/server/storage/itemptr.h
/usr/include/postgres-xc/server/storage/large_object.h
/usr/include/postgres-xc/server/storage/latch.h
/usr/include/postgres-xc/server/storage/lmgr.h
/usr/include/postgres-xc/server/storage/lock.h
/usr/include/postgres-xc/server/storage/lwlock.h
/usr/include/postgres-xc/server/storage/off.h
/usr/include/postgres-xc/server/storage/pg_sema.h
/usr/include/postgres-xc/server/storage/pg_shmem.h
/usr/include/postgres-xc/server/storage/pmsignal.h
/usr/include/postgres-xc/server/storage/pos.h
/usr/include/postgres-xc/server/storage/predicate.h
/usr/include/postgres-xc/server/storage/predicate_internals.h
/usr/include/postgres-xc/server/storage/proc.h
/usr/include/postgres-xc/server/storage/procarray.h
/usr/include/postgres-xc/server/storage/procsignal.h
/usr/include/postgres-xc/server/storage/reinit.h
/usr/include/postgres-xc/server/storage/relfilenode.h
/usr/include/postgres-xc/server/storage/s_lock.h
/usr/include/postgres-xc/server/storage/shmem.h
/usr/include/postgres-xc/server/storage/sinval.h
/usr/include/postgres-xc/server/storage/sinvaladt.h
/usr/include/postgres-xc/server/storage/smgr.h
/usr/include/postgres-xc/server/storage/spin.h
/usr/include/postgres-xc/server/storage/standby.h