(fix_new_exp): Handle O_add by creating an expression-valued symbol, and

(fix_new_exp): Handle O_add by creating an expression-valued symbol, and
calling fix_new_exp recursively.
(adjust_reloc_syms): If a fixup's symbol value is a sum of an undefined symbol
and a constant, fold the constant into the fixup, and refer to the undefined
symbol directly.  Then process the fixup again from scratch.
(write_object_file): Before calling adjust_reloc_syms, make a pass through the
symbol list trying to resolve values.

(print_fixup): New routine, for debugging.
(write_relocs): Call bfd_install_relocation.  Deleted various hacks for working
around problems with bfd_perform_relocation.