ELF: Discard non-alloc sections without section header

ELF: Discard non-alloc sections without section header

Discard non-alloc sections when section headers are stripped.

bfd/

	PR ld/25617
	* elf.c (_bfd_elf_assign_file_positions_for_non_load): Skip
	non-load sections without section header.
	(_bfd_elf_write_object_contents): Don't set the sh_name field
	without section header.  Write out the .shstrtab section only
	if its sh_offset field isn't -1.

binutils/

	PR ld/25617
	* objcopy.c (is_strip_section_1): Remove non-alloc sections for
	--strip-section-headers.

ld/

	PR ld/25617
	* ldlang.c (lang_discard_section_p): Discard non-alloc sections
	if we are stripping section headers.