PR ipa/81360
	* cgraph.h (symtab_node::output_to_lto_symbol_table_p): Declare
	* symtab.c: Include builtins.h
	(symtab_node::output_to_lto_symbol_table_p): Move here
	from lto-streamer-out.c:output_symbol_p.
	* lto-streamer-out.c (write_symbol): Turn early exit to assert.
	(output_symbol_p): Move all logic to symtab.c
	(produce_symtab): Update.

	* lto.c (unify_scc): Register prevailing trees, not trees to be freed.
	(read_cgraph_and_symbols): Use
	symtab_node::output_to_lto_symbol_table_p.

From-SVN: r257490