Yubin Ruan <ablacktshirt@gmail.com> spotted that I was conflating
the base-relative address offset in ElfW(Rel) and ElfW(Rela) addresses
from DT_REL and DT_RELA sections with the absolute addresses from
ElfW(Dyn) pointer entries.

This fixes a long-standing TODO about removing the hack in addr()
where there was guesswork about whether the address being was
base-relative or absolute.