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

	* elf-bfd.h (struct elf_backend_data): Add struct elf_backend_data
	param to elf_backend_copy_indirect_symbol.
	(_bfd_elf_link_hash_copy_indirect): Likewise.
	* elflink.h (elf_add_default_symbol, elf_fix_symbol_flags): Adjust
	calls to copy_indirect_symbol.
	* elf32-hppa.c (elf32_hppa_copy_indirect_symbol): Likewise.
	* elf32-i386.c (elf_i386_copy_indirect_symbol): Likewise.
	* elf32-s390.c (elf_s390_copy_indirect_symbol): Likewise.
	* elf64-ppc.c (ppc64_elf_copy_indirect_symbol): Likewise.
	* elf64-s390.c (elf_s390_copy_indirect_symbol): Likewise.
	* elf64-x86-64.c (elf64_x86_64_copy_indirect_symbol): Likewise.
	* elfxx-ia64.c (elfNN_ia64_hash_copy_indirect): Likewise.
	* elfxx-mips.c (_bfd_mips_elf_copy_indirect_symbol): Likewise.
	* elfxx-mips.h (_bfd_mips_elf_copy_indirect_symbol): Likewise.
	* elf.c (_bfd_elf_link_hash_copy_indirect): Likewise.  Properly
	test refcounts for "used" values.