* avr-dis.c: Include libiberty.h (for xmalloc).
	(struct avr_opcodes_s): Remove 'bin_mask' field (it's
	automatically computed in the init routine).
	(AVR_INSN): No longer provide bin_mask field in initializer.
	(avr_opcodes_s): Declare as const.
	(print_insn_avr): Store the bin_mask field in a separate table
	(allocated with xmalloc); iterate through it at the same time as
	we iterate through the opcodes.