dont make all the changes
just make these changes over here in the link
you need to uncomment these
# LOCAL_WHOLE_STATIC_LIBRARIES += cocos_extension_static
LOCAL_WHOLE_STATIC_LIBRARIES += cocos_extension_static
#include "extensions/cocos-ext.h" where you want the extensions to be.
on the first build it will compile all the extensions file.
i recently got over these while working with extensions, nothing other than these
If you still face issues.. then tell us the exact error you are getting
we will help you.