which package has pg_config ?

I was used to the postgresql-server-dev-XXX packages to have
pg_config (the one specific to the given version) but I found
that file missing from the package for version 11:
https://travis-ci.org/qgis/QGIS/jobs/651881033#L769

How do I obtain a pg_config bound to PostgreSQL 11 installation ?

--strk;