Add convenience libraries to the include path

[Zé]

I'm refactoring a small C++ project and in the process I've migrated a 
component to a convenience library.

I would like to add the convenience library's root directory to the 
project's include path, but I haven't found any reference on how to do 
this.  The closest I could find was adding ${srcdir} to the include 
path, but that doesn't sound right.

Does anyone know how to pull this off?



Zé