RFC: Improve error message for unresolved symbols because of --no-add-needed

[Nick Clifton]

Hi Guys,

> bfd/ChangeLog
> 2009-10-29  Nick Clifton  <nickc@redhat.com>
> 
> 	* elflink.c (elf_link_add_object_symbols): Improve error
> 	message generated when a symbol is left unresolved because a
>         --no-add-needed command line option has prevented the
> 	inclusion of the DSO defining it.

Well I had no objections to this, so I have gone ahead and checked it in.

Cheers
   Nick