Feature: Allow chaning makepkg OPTIONS like debug/lto to speed up builds

[systemofapwne]

Right now, two packages are built: The actual package and a package-debug. This stems from makepkg having debug set in OPTIONS of makepkg.conf.
Having a way to globally control OPTIONS of makepkg (or even better: The full makepkg.conf) would be fantastic.
In principle, one could use a custom builder image with the new feature of #271. But that sounds a bit overkill to me as it also brings the burden to either publishing it on a (public or private) registry and to keep it updated via CI/CD.

[Lukas-Heiligenbrunner]

Yes, thats a good idea!
In the future i want to build a settings page where this might be configured (and also some of the options which are env variables now)