x86: Add is_x86_elf

x86: Add is_x86_elf

Share is_x86_elf in elf32-i386.c and elf64-x86-64.c.

	* elf32-i386.c (is_i386_elf): Removed.
	(elf_i386_check_relocs): Replace is_i386_elf with is_x86_elf.
	(elf_i386_size_dynamic_sections): Likewise.
	(elf_i386_relocate_section): Likewise.
	* elf64-x86-64.c (is_x86_64_elf): Removed.
	(elf_x86_64_check_relocs): Replace is_x86_64_elf with
	is_x86_elf.
	(elf_x86_64_size_dynamic_sections): Likewise.
	(elf_x86_64_relocate_section): Likewise.
	* elfxx-x86.c (_bfd_x86_elf_link_hash_table_create): Initialize
	target_id.
	* elfxx-x86.h (elf_x86_link_hash_table): Add target_id.
	(is_x86_elf): New.