Refactored detecting several Apple-related technologies.

Now the HAVE_* macros are set using cvconfig.h. Previously most
of them already were there, but were always undefined. One,
HAVE_COCOA, I had to add.

This also makes the CMake code more consistent; now, WITH_* variables
are always checked in cmake/*, while HAVE_* variables are checked in
modules/highgui/CMakeLists.txt.

cmake/OpenCVFindLibsGUI.cmake

@@ -65,3 +65,12 @@ if(WITH_OPENGL)
     endif()
   endif()
 endif(WITH_OPENGL)
+
+# --- Carbon & Cocoa ---
+if(APPLE)
+  if(WITH_CARBON)
+    set(HAVE_CARBON YES)
+  elif(NOT IOS)
+    set(HAVE_COCOA YES)
+  endif()
+endif()