Fix sketchbook finding for newer versions of macOS IDE

Author: TellowKrinkle

cmake/Platform/System/SketchbookFinder.cmake

@@ -10,7 +10,11 @@ function(_get_user_preferences_file_path _return_var)
 
     if (${CMAKE_HOST_UNIX})
         if (${CMAKE_HOST_APPLE}) # Mac OS X
-            set(dir_path "$ENV{HOME}/Library/Processing/${preferences_file_name}")
+            if (EXISTS "$ENV{HOME}/Library/Arduino15/${preferences_file_name}")
+                set(dir_path "$ENV{HOME}/Library/Arduino15/${preferences_file_name}")
+            else ()
+                set(dir_path "$ENV{HOME}/Library/Processing/${preferences_file_name}")
+            endif ()
         else () # Linux
             if (EXISTS "$ENV{HOME}/.arduino15/${preferences_file_name}")
                 set(dir_path "$ENV{HOME}/.arduino15/${preferences_file_name}")