This fixes parsing a file containing ELF attributes with very large tag values.

This fixes parsing a file containing ELF attributes with very large tag values.

	PR binutils/18570
	* elf-attrs.c (obj_attr_size): Use an unsigned int type for the tag.
	(write_obj_attribute): Likewise.
	(elf_new_obj_attr): Likewise.
	(bfd_elf_get_obj_attr_int): Likewise.
	(bfd_elf_add_obj_attr_int): Likewise.
	(bfd_elf_add_obj_attr_string): Likewise.
	(bfd_elf_add_obj_attr_int_string): Likewise.
	(gnu_obj_attrs_arg_type): Likewise.
	(_bfd_elf_obj_attrs_arg_type): Likewise.
	(_bfd_elf_parse_attributes): Likewise.
	(_bfd_elf_merge_unknown_attribute_list): Likewise.
	* elf-bfd.h (struct obj_attribute_list): Likewise.
	Update prototypes.