ci: compile with -Og where applicable.
To improve performance of check-world, and improve debugging, without
significantly slower builds (they're cached anyway).
This makes freebsd check-world run in 8.5 minutes rather than 15 minutes.
Author: Justin Pryzby <pryzbyj@telsasoft.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/
20220310220611.GH28503@telsasoft.com