A lot of the packages use the same script (pull_and_build_from_git) or some custom compiler option choice.
This information is usually directly copied into their scripts or json files in each and every package.

However, besides package-specific tweaks, the actual selection of which compiler to use and what options to feed it is generally uniform across all packages. It'd be good to at least attempt to centrally locate that option so that new packages or package upgrades don't have to reinvent the wheel each time.