PR ld/12851

	PR ld/12851
	* elflink.c (_bfd_elf_gc_mark_extra_sections): New function.
	(elf_gc_sweep): Don't treat debug and sections like .comment
	specially here.
	(bfd_elf_gc_sections): Treat note sections as gc roots only when
	not part of a group.  Always call gc_mark_extra_sections.
	* elf-bfd.h (_bfd_elf_gc_mark_extra_sections): Declare.
	* elfxx-target.h (elf_backend_gc_mark_extra_sections): Default to
	_bfd_elf_gc_mark_extra_sections.
	* elf32-arm.c (elf32_arm_gc_mark_extra_sections): Call
	_bfd_elf_gc_mark_extra_sections.
	* elf32-tic6x.c (elf32_tic6x_gc_mark_extra_sections): Likewise.