LibBoostFooer depends PUBLICLY on libFooer, and PRIVATELY on Boost
Also this example explores the possibility of building the needed dependencies
(libFooer and libFoo) if they are not found. A 3rdparty directory contains
the symlinks to the two directories. If libFooer is not found or provided,
it will be built along with libFoo, and installed together with libBoostFooer.
- How to deal with existing targets for the dependencies, if the target already exists
because it has been built previously (e.g. monolithic build) it can be renamed
with an alias to match the name when imported. If the dependency does not exist,
then it must be found using
find_package().