Schema qualify pg_catalog functions and tables
To better protect against https://wiki.postgresql.org/wiki/A_Guide_to_CVE-2018-1058:_Protect_Your_Search_Path
during PostGIS install and upgrade.
The focus is on CREATE EXTENSION / select postgis_extensions_upgrade() / ALTER EXTENSION
I think the tables to change are not necessary, although in theory we should be since someone could define such tables in the schema they install postgis (like a view that calls a function). I will be replacing these as well to prevent a rogue actor forcing some change by replacing key tables/views in pg_catalog.
Sadly I think this changes quite a few files.