CMP0019

Do not re-expand variables in include and link information.

CMake 2.8.10 and lower re-evaluated values given to the include_directories, link_directories, and link_libraries commands to expand any leftover variable references at the end of the configuration step. This was for strict compatibility with VERY early CMake versions because all variable references are now normally evaluated during CMake language processing. CMake 2.8.11 and higher prefer to skip the extra evaluation.

The OLD behavior for this policy is to re-evaluate the values for strict compatibility. The NEW behavior for this policy is to leave the values untouched.

This policy was introduced in CMake version 2.8.11. CMake version 3.9.6 warns when the policy is not set and uses OLD behavior. Use the cmake_policy command to set it to OLD or NEW explicitly.