Targets may not link directly to themselves.
CMake 2.8.12 and lower allowed a build target to link to itself directly with a target_link_libraries() call. This is an indicator of a bug in user code.
The OLD behavior for this policy is to ignore targets which list themselves in their own link implementation. The NEW behavior for this policy is to report an error if a target attempts to link to itself.
This policy was introduced in CMake version 3.0. CMake version 3.0.20140506-g0eb60 warns when the policy is not set and uses OLD behavior. Use the cmake_policy command to set it to OLD or NEW explicitly.
