* elf64-x86-64.c (struct elf_x86_64_backend_data): New type.

	* elf64-x86-64.c (struct elf_x86_64_backend_data): New type.
	(get_elf_x86_64_backend_data, GET_PLT_ENTRY_SIZE): New macros.
	(elf_x86_64_arch_bed): New variable.
	(elf_backend_arch_data): New macro.
	(elf_x86_64_adjust_dynamic_symbol): Use GET_PLT_ENTRY_SIZE.
	(elf_x86_64_allocate_dynrelocs): Likewise.
	(elf_x86_64_relocate_section): Likewise.
	(elf_x86_64_plt_sym_val): Likewise.
	(elf_x86_64_finish_dynamic_symbol): Use elf_x86_64_backend_data
	parameters for PLT details.
	(elf_x86_64_finish_dynamic_sections): Likewise.