re PR lto/61886 (LTO breaks fread with _FORTIFY_SOURCE=2)

re PR lto/61886 (LTO breaks fread with _FORTIFY_SOURCE=2)

	PR ipa/61886
	* symtab.c (ultimate_transparent_alias_target): New inline function.
	(symbol_table::assembler_names_equal_p): New method; break out from ...
	(symbol_table::decl_assembler_name_equal): ... here.
	(symbol_table::change_decl_assembler_name): Also update names and
	translation links of transparent aliases.
	(symtab_node::dump_base): Dump transparent_alias.
	(symtab_node::verify_base): Implement basic transparent alias
	verification.
	(symtab_node::make_decl_local): Support localization of weakrefs;
	recurse to transparent aliases; set TREE_STATIC.
	(symtab_node::ultimate_alias_target_1): Handle visibility of
	transparent aliases.
	(symtab_node::resolve_alias): New parmaeter transparent; handle
	transparent aliases; recurse to aliases of aliases to fix comdat
	groups.
	(symtab_node::get_partitioning_class): Handle transparent aliases.
	* ipa-visibility.c (cgraph_externally_visible_p,
	varpool_node::externally_visible_p): Visibility of transparent alias
	depends on its target.
	(function_and_variable_visibility): Do not tweak visibility of
	transparent laiases.
	(function_and_variable_visibility): Likewise.
	* ipa.c (symbol_table::remove_unreachable_nodes): Clear
	transparent_alias flag.
	* alias.c (cgraph_node::create_alias, cgraph_node::get_availability):
	Support transparent aliases.
	* cgraph.h (symtab_node): Update prototype of resolve_alias;
	add transparent_alias flag.
	(symbol_table: Add assembler_names_equal_p.
	(symtab_node::real_symbol_p): Skip transparent aliases.
	* cgraphunit.c (cgraph_node::reset): Reset transparent_alias flag.
	(handle_alias_pairs): Set transparent_alias for weakref.
	(cgraph_node::assemble_thunks_and_aliases): Do not asemble transparent
	aliases.
	* lto-cgraph.c (lto_output_node): When outputting same_comdat_group
	skip symbols not put into boundary; stream transparent_alias.
	(lto_output_varpool_node): Likewise.
	(input_overwrite_node, input_varpool_node): Stream transparent alias.
	* varpool.c (ctor_for_folding, varpool_node::get_availability,
	varpool_node::assemble_aliases,
	symbol_table::remove_unreferenced_decls): Handle transparent aliase.
	(varpool_node::create_alias): Set transparent_alias.

	* lto-partition.c (add_symbol_to_partition_1, contained_in_symbol,
	rename_statics, rename_statics): Handle transparent aliases.

From-SVN: r231373