[Gnewsense-dev] Builder update: overrides

[Sam Geeraerts]

People using Builder should pay attention to the latest revision (422). 
It introduces some functions and files to determine Section overrides 
more dynamically. For this the *Override options in conf/distributions 
have to be changed like they were in gen-repo. You can do this manually, 
but just running gen-repo again should work too.