ApprovalTests.cpp's tests and examples should never be built when used as a sub-project #179
Description
The intention in this project's CMake scripts is never to build our tests and examples by default, when we are used as a sub-project.
However, a mistake in this CMake code meant that if a parent project had set NOT_SUBPROJECT to ON, then our tests and examples would be built and run.
This was fixed in commit 94192f8.