Kohányi Róbert authored Sep 18, 2018 and Brad King committed Sep 25, 2018

* Separate find_library calls to find Release and Debug libs.
* Using select_library_configurations to properly populate required
  variables (similar to FindZLIB).
* Setting Release and Debug specific properties
  (IMPORTED_CONFIGURATIONS_<CONFIG> and IMPORTED_LOCATION_<CONFIG>).
* Falling back to setting just IMPORTED_LOCATION if
  GLUT_glut_LIBRARY_RELEASE or GLUT_glut_LIBRARY_DEBUG are not defined.

This enables proper linking on Windows.

Fixes: #17037