* elfcode.h (struct bfd_preserve): New.

	(elf_object_p): Replace preserved_* vars with instance of above.
	Save and restore arch_info pointer rather than arch, mach so that
	more cases can be restored.  Save and restore new section_tail,
	section_htab structure, and init appropriately.  Move "rest of
	section header" code so that i_shdrp needs no NULL initialisation.
	Free old section_htab on success.
	* elfcore.h (elf_core_file_p): Likewise.