Fix panic when parsing DWARF 2 line info for empty section

[AetiasHax]

mwccarm emits individual .text sections for each function, and in some cases it can emit an empty .text section which will be ignored by objdiff. This causes the DWARF 2 line info parser to unwrap a None value when attempting to iterate to the empty section.

Now it's fixed by letting the None section value cascade up into the lines variable instead of unwrapping it.

[encounter]

Thanks!