* elf-bfd.h (struct elf_backend_data): Added

* elf-bfd.h (struct elf_backend_data): Added
elf_backend_can_make_relative_eh_frame,
elf_backend_can_make_lsda_relative_eh_frame and
elf_backend_encode_eh_address.
(_bfd_elf_encode_eh_address): Declare.
(_bfd_elf_can_make_relative): Declare.
* elf-eh-frame.c (_bfd_elf_discard_section_eh_frame): Use new
hooks to decide whether to attempt to make_relative and
make_lsda_relative.
(_bfd_elf_write_section_eh_frame_hdr): Call encode_eh_address.
(_bfd_elf_can_make_relative): New.
(_bfd_elf_encode_eh_address): New.
* elf32-frv.c (frv_elf_use_relative_eh_frame): New.
(frv_elf_encode_eh_address): New.
(elf_backend_can_make_relative_eh_frame): Define.
(elf_backend_can_make_lsda_relative_eh_frame): Define.
(elf_backend_encode_eh_address): Define.
* elfxx-target.h
(elf_backend_can_make_relative_eh_frame): Define.
(elf_backend_can_make_lsda_relative_eh_frame): Define.
(elf_backend_encode_eh_address): Define.
(elfNN_bed): Add them.