Remove use of __APPLE_CC__
Remove use of __APPLE_CC__

__APPLE_CC__ is an obsolete macro for clang version. Instead, conditionalize by platform, not compiler. Hoisted the same snippit from VTK itself.

lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples,lorensen/VTKExamples