Tidy dwarf1 cached section contents

	* dwarf1.c (_bfd_dwarf1_cleanup_debug_info): New function.
	* libbfd-in.h (_bfd_dwarf1_cleanup_debug_info): Declare.
	* elf.c (_bfd_elf_close_and_cleanup): Call it.
	* elf-bfd.h (struct elf_obj_tdata): Make dwarf1_find_line_info
	a void*.
	* libbfd.h: Regenerate.