PR29647, objdump -S looping

Fuzzed input with this in .debug_line
  [0x0000003b]  Special opcode 115: advance Address by 8 to 0x401180 and Line by -2 to -1

	PR 29647
	* objdump.c (print_line): Don't decrement line number here..
	(dump_lines): ..do so here instead, ensuring loop terminates.