[rfa/dwarf] Kill some more unnecessary global variables

[Jim Blandy]

Daniel Jacobowitz <drow@mvista.com> writes:

> Now that we pass the section to dwarf2_read_section, we don't need to
> pass the offset and size parameters also.  After removing them, it turns out
> that the global offset variables are only:
>   - passed to dwarf2_read_section
>   - tested for non-zero-ness to indicate presence of the section
> And testing the section pointer works just as well, so we can remove the
> offsets.
> 
> This is part of the global state in dwarf2read crusade.  The remaining
> section info is probably going to move into the objfile as per-objfile data,
> but I wanted to prune the deadwood first.
> 
> OK?

Yes!  Please commit.