Change ld "notice" interface for better handling of indirect symbols

Change ld "notice" interface for better handling of indirect symbols

The main aim of this change was to have non_ir_ref set correctly on
new indirect symbols.  I could have added a "copy" param to the "notice"
function, so that indirect symbols could be created in plugin_notice,
but it seemed cleaner to create indirect syms earlier and pass them
rather than "string" to "notice".

include/
	* bfdlink.h (struct bfd_link_callbacks <notice>): Remove "string"
	param, add "inh".
bfd/
	* coff-aux.c (coff_m68k_aux_link_add_one_symbol): Only call "notice"
	here when not calling the generic add_symbol function.  Formatting.
	Correct handling of indirect symbols.  Update notice call.
	* elflink.c (_bfd_elf_notice_as_needed): Update notice call.
	* linker.c (_bfd_generic_link_add_one_symbol): Create indirect
	symbols early.  Update notice call.  Add comments regarding weak
	symbols vs. indirect.
ld/
	* ldmain.c (notice): Update args.
	* plugin.c (plugin_notice): Likewise.  Follow warning sym link.
	Handle new indirect symbol.