* elf64-alpha.c: Initial implementation of relaxation --

    * elf64-alpha.c: Initial implementation of relaxation --
        (struct alpha_elf_link_hash_entry): Add use_count member.
        (elf64_alpha_check_relocs): Initialize and increment it.
        (elf64_alpha_can_merge_gots): Check it when considering merging.
        (elf64_alpha_merge_gots): Drop entries with zero use.
        (elf64_alpha_calc_got_offsets_for_symbol): Likewise.
        (elf64_alpha_always_size_sections): Split out got sizing ...
        (elf64_alpha_size_got_sections): ... here.  New function.
        (elf64_alpha_relax_find_reloc_ofs): New function.
        (elf64_alpha_relax_with_lituse): Likewise.
        (elf64_alpha_relax_without_lituse): Likewise.
        (elf64_alpha_relax_opt_call): Likewise.
        (elf64_alpha_relax_section): Likewise.
        (elf64_alpha_add_symbol_hook): Likewise.
        (elf64_alpha_howto_table): Implement GPRELHIGH/LOW & IMMED_GP_16.
        (elf64_alpha_relocate_section): Likewise.
        (bfd_elf64_bfd_relax_section): Define.
        (elf_backend_add_symbol_hook): Likewise.