message: Fix for older cmake
  GREATER_EQUAL was introduces with cmake 3.7
diff: @@ -334,7 +334,7 @@ visionaray_add_library(visionaray
  # MSVC + CUDA: link with legacy stdio library
  -if (MSVC_VERSION GREATER_EQUAL 1900 AND VSNRAY_ENABLE_CUDA AND CUDA_FOUND)
  +if (MSVC_VERSION GREATER 1800 AND VSNRAY_ENABLE_CUDA AND CUDA_FOUND)
  target_link_libraries(visionaray legacy_stdio_definitions.lib)
  endif()
  