gcc and updates of packages in core

Hello, I tried to build zathura and gimp and it didn't work. But if I try with gcc 4.9.2 I can build them without a problem. I still don't know crux very well, but I'm almost sure it's related to the release cycle of crux but I can't find the information. So my questions are: - When a new version of crux is released, some collections are updated. I think core, opt and xorg. Other ones ? And before the release, the ports are not updated, only if there is an update in the same branch. I mean gcc has been updated from 4.8.3 to 4.8.4. - If my assumption is right, what is the best option when a package in core need an update ? To write a local port ? Thank you! Best regards, Cédric