title: Bitbake runtime vs build dependency
body: <p>I am having trouble understanding the bitbake recipes. (I have some poorly written I need to modify, I usually would read and understand the whole mechanism but sadly I am on a tight schedule).
  Can you please help me understand the difference between RDEPENDS and DEPENDS. I read the reference and I know that they stand for runtime dependency and build dependency respectively, but what is the effect on it in a bitbake recipe?
  As far as I understand, if a package A depends on another B, B has to be built and ready to enable A to build. Bitbake isn't related to the runtime, it's only there for building and deploying the packages. So what is the difference?</p>