Re: Move nm.c cached line number info to bfd usrdata

Commit e3f450f3 resulted in a nm -l segfault on object files
without undefined symbols.  Fix that, and be paranoid about bfd
section count changing.

	* nm.c (struct lineno_cache): Add seccount.
	(free_lineno_cache): Don't segfault on NULL lc->relocs.
	(print_symbol): Stash section count when creating arrays.