PR32560 stack-buffer-overflow at objdump disassemble_bytes

There's always someone pushing the boundaries.

	PR 32560
	* objdump.c (MAX_INSN_WIDTH): Define.
	(insn_width): Make it an unsigned long.
	(disassemble_bytes): Use MAX_INSN_WIDTH to size buffer.
	(main <OPTION_INSN_WIDTH>): Restrict size of insn_width.