[patch] compress debug sections

[Rafael Espíndola]

> This should be ok. As we (and Jim) discussed, we should only create a
> new fragment for things that could be resized - and given that we run
> computeSizeAndOffsets for debug info I'm reasonably confident that we
> should never resize parts of the debug info section. Adding a couple
> of asserts might be good though.

We do create them for .debug_frame at least. Not sure if that is
relevant for this or not.

Cheers,
Rafael