Try adding this line at the end of the boards.txt file:
atmega328bb.build.variant=standard
Or if that doesn't work, try this one:
atmega328bb.build.variant=arduino:standard
Try adding this line at the end of the boards.txt file:
atmega328bb.build.variant=standard
Or if that doesn't work, try this one:
atmega328bb.build.variant=arduino:standard