/usr/include/postgresql/9.3/server/lib/ is in postgresql-server-dev-9.3 9.3.4-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/postgresql/9.3/server/lib/binaryheap.h
/usr/include/postgresql/9.3/server/lib/ilist.h
/usr/include/postgresql/9.3/server/lib/stringinfo.h
/usr/include/postgresql/9.3/server/libpq/auth.h
/usr/include/postgresql/9.3/server/libpq/be-fsstubs.h
/usr/include/postgresql/9.3/server/libpq/crypt.h
/usr/include/postgresql/9.3/server/libpq/hba.h
/usr/include/postgresql/9.3/server/libpq/ip.h
/usr/include/postgresql/9.3/server/libpq/libpq-be.h
/usr/include/postgresql/9.3/server/libpq/libpq-fs.h
/usr/include/postgresql/9.3/server/libpq/libpq.h
/usr/include/postgresql/9.3/server/libpq/md5.h
/usr/include/postgresql/9.3/server/libpq/pqcomm.h
/usr/include/postgresql/9.3/server/libpq/pqformat.h
/usr/include/postgresql/9.3/server/libpq/pqsignal.h