[rfc] Fix problem with (maybe) non-relocated .opd section on powerpc64-linux

[Ulrich Weigand]

I wrote:

> I guess we could cache the result of symfile_relocate_debug_section
> on the .opd section for the objfile.

Huh, that's not as simple as I though: we're using target sections
here (not obj_sections) -- these are not even associated with any
objfile at this point ...

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com