CMake: Remove Old Version Policy

[ax3l]

The setting cmake_policy(SET CMP0048 OLD) in CMake files should be removed and logic be updated according to the new policy.

It warns on current CMake 3.11.4:

CMake Deprecation Warning at isaac-1.4.0/lib/cmake/ISAAC/ISAACConfig.cmake:20 (cmake_policy):
  The OLD behavior for policy CMP0048 will be removed from a future version
  of CMake.

  The cmake-policies(7) manual explains that the OLD behaviors of all
  policies are deprecated and that a policy should be set to OLD only under
  specific short-term circumstances.  Projects should be ported to the NEW
  behavior and not rely on setting a policy to OLD.