Contributing to a project doesn't mean you get to ignore the license; if you submit a patch for readline, you still have to GPL your app that links to it.
The LLVM project isn't controlled by a single entity, but it does get a lot of code from "commercial" users, so those users chose a license that works well for them. (It ensures that any future contributions will be usable under an acceptable license.) Admittedly the LGPL would also be fine, but ... that's not what they picked.
The LLVM project isn't controlled by a single entity, but it does get a lot of code from "commercial" users, so those users chose a license that works well for them. (It ensures that any future contributions will be usable under an acceptable license.) Admittedly the LGPL would also be fine, but ... that's not what they picked.