PR26103, Assertion failure with symbols defined in link-once sections

PR26103, Assertion failure with symbols defined in link-once sections

	PR 26103
	* elflink.c (elf_link_add_archive_symbols): Exclude undefined
	symbols that were defined in discarded sections.
	* cofflink.c (coff_link_check_archive_element): Likewise.
	(coff_link_add_symbols): Set indx to -3 for symbols defined in
	discarded sections.
	(_bfd_coff_write_global_sym): Don't emit such symbols.
	libcoff-in.h (struct coff_link_hash_entry): Update indx comment.
	libcoff.h: Regenerate.