The parsing library shouldn't really care about keeping track of these.
Instead, add __dict__ and getattr()/setattr() to all of the lldwarf
objects so higher layers can store the offset if they want.
DwarfDie is special in two ways:
1. We want to store an offset for the DIE so we know where to parse
sibling and children entries.
2. For some attributes, we need to store an offset so we know where to
find them later.
Both of these are changed to be relative to the CU rather than the
buffer.
I wrote all of this code a few months back and am just now getting
around to committing it. The low-level DWARF parsing library is pretty
solid, although it only implements a subset of DWARF so far. The CLI and
higher-level interface are experimental.