make sync_schema_props_perms(<computed rtype>) work as expected It currently ends up with an ExecutionError while we want to synchronize permissions. This makes 3.21.1 migration of any application using computed relation crashing. Also, remove pre 3.6 compat code in hooks that prevent living schema update on computed relation's permission changes.

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules.tmpl)