Do not treat
DEFINITIONS as a built-in directory property.
OLD behavior for this policy is to provide the list of flags given
so far to the
add_definitions() command. The
NEW behavior is
to behave as a normal user-defined directory property.
This policy was introduced in CMake version 3.3.
CMake version 3.6.2 warns when the policy is not set and uses
OLD behavior. Use the
cmake_policy() command to set
OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.