/usr/include/postgresql/8.4/server/commands/ is in postgresql-server-dev-8.4 8.4.11-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/postgresql/8.4/server/commands/alter.h
/usr/include/postgresql/8.4/server/commands/async.h
/usr/include/postgresql/8.4/server/commands/cluster.h
/usr/include/postgresql/8.4/server/commands/comment.h
/usr/include/postgresql/8.4/server/commands/conversioncmds.h
/usr/include/postgresql/8.4/server/commands/copy.h
/usr/include/postgresql/8.4/server/commands/dbcommands.h
/usr/include/postgresql/8.4/server/commands/defrem.h
/usr/include/postgresql/8.4/server/commands/discard.h
/usr/include/postgresql/8.4/server/commands/explain.h
/usr/include/postgresql/8.4/server/commands/lockcmds.h
/usr/include/postgresql/8.4/server/commands/portalcmds.h
/usr/include/postgresql/8.4/server/commands/prepare.h
/usr/include/postgresql/8.4/server/commands/proclang.h
/usr/include/postgresql/8.4/server/commands/schemacmds.h
/usr/include/postgresql/8.4/server/commands/sequence.h
/usr/include/postgresql/8.4/server/commands/tablecmds.h
/usr/include/postgresql/8.4/server/commands/tablespace.h
/usr/include/postgresql/8.4/server/commands/trigger.h
/usr/include/postgresql/8.4/server/commands/typecmds.h
/usr/include/postgresql/8.4/server/commands/user.h
/usr/include/postgresql/8.4/server/commands/vacuum.h
/usr/include/postgresql/8.4/server/commands/variable.h
/usr/include/postgresql/8.4/server/commands/version.h
/usr/include/postgresql/8.4/server/commands/view.h