/usr/share/postgresql/9.5/ is in postgresql-plperl-9.5 9.5.2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/postgresql/9.5/extension/
/usr/share/postgresql/9.5/extension/hstore_plperl--1.0.sql
/usr/share/postgresql/9.5/extension/hstore_plperl.control
/usr/share/postgresql/9.5/extension/hstore_plperlu--1.0.sql
/usr/share/postgresql/9.5/extension/hstore_plperlu.control
/usr/share/postgresql/9.5/extension/plperl--1.0.sql
/usr/share/postgresql/9.5/extension/plperl--unpackaged--1.0.sql
/usr/share/postgresql/9.5/extension/plperl.control
/usr/share/postgresql/9.5/extension/plperlu--1.0.sql
/usr/share/postgresql/9.5/extension/plperlu--unpackaged--1.0.sql
/usr/share/postgresql/9.5/extension/plperlu.control