close last arfile before processing current arfile

This also reduces peak memory a little.

	* dlltool.c (identify_search_archive): Close last_arfile earlier.
	Report an error if bfd_openr_next_archived_file returns the same
	bfd.  Localise variables.
	* nm.c (display_archive): Likewise.
	* objdump.c (display_any_bfd): Likewise.
	* size.c (display_archive): Likewise.