When copying the sh_link and sh_info fields in stripped section headers,
we also check if the sh_type, sh_flags, /sh_addralign and sh_entsize
fields of the output section match the output.  Since --only-keep-debug
turns all non-debug sections into SHT_NOBITS sections, the output
SHT_NOBITS type matches any input type.

bfd/

	PR binutils/18785
	* elf.c (_bfd_elf_copy_private_bfd_data): When copying the
	sh_link and sh_info fields in stripped section headers, we also
	check if the sh_type, sh_flags, /sh_addralign and sh_entsize
	fields of the output section match the output.  Since
	--only-keep-debug turns all non-debug sections into SHT_NOBITS
	sections, the output SHT_NOBITS type matches any input type.

binutils/testsuite/

	PR binutils/18785
	* binutils-all/objcopy.exp: Run strip-12.
	* binutils-all/strip-12.d: New file.
	* binutils-all/strip-12.s: Likewise.