Summary:
This does some preprataion for the Yoga CMake Build. The main change is removing the dedicated testutil top-level-directory and static library. This contains a method to count nodes using the event functions exposed to C++, along with a Java binding for the test utility (since the events don't have a Java binding). It is only used in a single place in a way that isn't very useful, so it simplifies things to treat is as source in the existing C++ test library.
This also separates the hand-written and generated UTs, like we are doing in the JS directory in D42207782.
Reviewed By: christophpurrer
Differential Revision: D42247762
fbshipit-source-id: f8a270e99d0315ba7fc608f2471333e7a7be9d79
