plugin: Use LDPT_ADD_SYMBOLS_V2 to get symbol type

plugin: Use LDPT_ADD_SYMBOLS_V2 to get symbol type

Since LTO plugin may generate more than one ltrans.o file from one input
IR object as LTO wrapper ignores -flto-partition=none:

lto-wrapper.c:608:

   604          /* Drop arguments that we want to take from the link line.  */
   605          case OPT_flto_:
   606          case OPT_flto:
   607          case OPT_flto_partition_:
   608            continue;

the LTO wrapper approach is not only slow but also unreliable.  Since
the LTO plugin API has been extended to add LDPT_ADD_SYMBOLS_V2 with
symbol type and section kind, we can use LDPT_ADD_SYMBOLS_V2 to get
symbol type, instead of invoking the LTO wrapper.

	PR binutils/25640
	* plugin.c (plugin_list_entry): Add has_symbol_type.
	(add_symbols_v2): New function.
	(bfd_plugin_open_input): Don't invoke LTO wrapper if LTO plugin
	provides symbol type.
	(try_load_plugin): Add LDPT_ADD_SYMBOLS_V2.
	(bfd_plugin_canonicalize_symtab): Use LTO plugin symbol type if
	available.