image: add some annotations for mx_image_set_from_buffer/data
image: add some annotations for mx_image_set_from_buffer/data

Fixes: http://bugzilla.clutter-project.org/show_bug.cgi?id=2688

jonnylamb/mx,clutter-project/mx,pwithnall/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx