Unsupported compiler error when linking with Intel compiler

@dzenanz, I just found this thread:2 errors when trying to build Unity+MagicLeap plugin
Is that the one you’re referring to?

One suggestion in that thread is to use the same compiler for ITK and the application. At the same time, Intel compilers are supposed to be interoperable with GCC. Intel compilers define both _GNUC_ and __INTEL_COMPILER for example. Perhaps this should be accommodated in the ITK CMake logic? Meaning, the itk_compiler_detection.h should set ITK_COMPILER_IS_GNU also in addition to ITK_COMPILER_IS_Intel, if it’s an Intel compiler.