PR 33858 Object Attributes v2 memory leaks

It is possble for elf_object_p to hit errors after or during the loop
processing sections with bfd_section_from_shdr.  That means we might
have some object attributes malloc'd.  They need cleaning up in
elf_object_p because bfd_check_format_matches only handles tidying of
bfd_alloc memory.

	* elfcode.h (elf_object_p): Free object attributes on failure.