Re: [rfa/dwarf] Use objfile_data mechanism for per-objfile data

[Jim Blandy <jimb@redhat.com>]

Wonderful!  So it turns out 'struct dwarf2_pinfo' has only one real
member, huh?  :)

I have to say, 'dwarf2_per_objfile_data', 'struct
dwarf2_per_objfile_data', and 'dwarf2_per_objfile' are not my favorite
cluster of names.  It took me a few passes to get it straight.  (Yes,
I should have gotten more sleep, but I suspect there are others who
work under the same conditions...)

How about:
- 'dwarf2_objfile_data_key' for the 'struct objfile_data', and
- 'struct dwarf2_objfile' and 'dwarf2_objfile' for the actual
  per-objfile datatype and the global pointer to the current instance?

(Is that any better?  I think suffixes like "_data" really only belong
on things whose type is unspecified at the point where the name
appears, like 'void *' pointers, or objects related to them.  I mean,
everything is "data"; if you're going to give something a
generic-sounding name, that should be because you're emphasizing the
genericness of it.)

The lower-case implicit-parameter macros bug me.  But I assume they're
going away soon, and upper-casing them would make the patch huge,
right?