* elf.c (assign_section_numbers): Cope gracefully with sections
which have SHF_LINK_ORDER set but no sh_link set up.
* elflink.c (elf_get_linked_section_vma): Likewise.
* elfxx-ia64.c (elf_backend_link_order_error_handler): New. Set
it to NULL.
* elfxx-target.h (elf_backend_link_order_error_handler): New.
Set it to _bfd_default_error_handler.
(elfNN_bed): Add elf_backend_link_order_error_handler.