Error on non-existent dependency in add_dependencies.
CMake 2.8.12 and lower silently ignored non-existent dependencies
listed in the
The OLD behavior for this policy is to silently ignore non-existent
dependencies. The NEW behavior for this policy is to report an error
if non-existent dependencies are listed in the
This policy was introduced in CMake version 3.0. CMake version 3.6.2 warns when the policy is not set and uses OLD behavior. Use the cmake_policy command to set it to OLD or NEW explicitly.
OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.