x86: Add elf_x86_backend_data

x86: Add elf_x86_backend_data

Add plt0_pad_byte and target_os fields to elf_x86_link_hash_table.
Replace elf_i386_backend_data and elf_x86_64_backend_data with
elf_x86_backend_data.

	* elf32-i386.c (elf_i386_backend_data): Removed.
	(get_elf_i386_backend_data): Likewise.
	(elf_i386_arch_bed): Replace elf_i386_backend_data with
	elf_x86_backend_data.
	(elf_i386_get_synthetic_symtab): Likewise.
	(elf_i386_nacl_arch_bed): Likewise.
	(elf_i386_vxworks_arch_bed): Likewise.
	(elf_i386_relocate_section): Check target_os instead of
	is_vxworks.
	(elf_i386_finish_dynamic_symbol): Likewise.
	(elf_i386_finish_dynamic_sections): Use htab->plt0_pad_byte.
	Check target_os instead of is_vxworks.
	(elf_i386_link_setup_gnu_properties): Remove normal_target and
	is_vxworks.  Initialize plt0_pad_byte.
	* elf64-x86-64.c (elf_x86_64_backend_data); Removed.
	(get_elf_x86_64_arch_data): Likewise.
	(get_elf_x86_64_backend_data): Likewise.
	(elf_x86_64_arch_bed): Replace elf_x86_64_backend_data with
	elf_x86_backend_data.
	(elf_x86_64_get_synthetic_symtab): Likewise.
	(elf_x86_64_nacl_arch_bed): Likewise.
	(elf_x86_64_link_setup_gnu_properties): Remove is_vxworks and
	normal_target.  Initialize plt0_pad_byte.
	* elfxx-x86.c (elf_x86_allocate_dynrelocs): Check target_os
	instead of is_vxworks.
	(_bfd_x86_elf_size_dynamic_sections): Likewise.
	(_bfd_x86_elf_finish_dynamic_sections): Likewise.
	(_bfd_x86_elf_adjust_dynamic_symbol): Likewise.
	(_bfd_x86_elf_link_hash_table_create): Initialize target_os.
	(_bfd_x86_elf_link_setup_gnu_properties): Remove is_vxworks.
	Update normal_target.  Set up plt0_pad_byte.  Check target_os
	instead of is_vxworks.
	* elfxx-x86.h (elf_x86_target_os): New.
	(elf_x86_backend_data): Likewise.
	(get_elf_x86_backend_data): Likewise.
	(elf_x86_link_hash_table): Remove is_vxworks.  Add plt0_pad_byte
	and target_os.
	(elf_x86_init_table): Remove normal_target and is_vxworks.  Add
	plt0_pad_byte.