[CMake] Convenience libraries support

[Francis Leblanc]

Hi everyone,

Convenience libraries support in CMake was needed for our project, so I decided to take a look at the source code and see what could be done.
I've managed to make it work relatively quickly, thanks to the comments and the way the code is written !! :D
I don't know if it's supported in other languages/platforms, but it's a really nice feature to have in Linux C/C++, especially with big projects with circular dependencies.

I would like to know what is the process of submitting code, and what are the chances you integrate this feature in the public version of CMake.

Thanks,
Francis Leblanc