The variable_requires() command should not be called.
This command was introduced in November 2001 to perform some conditional logic. It has long been replaced by the if() command.
CMake >= 3.0 prefer that this command never be called. The OLD behavior for this policy is to allow the command to be called. The NEW behavior for this policy is to issue a FATAL_ERROR when the command is called.
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.
