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
	* lto-streamer.h (lto_symtab_merge_decls, lto_symtab_merge_symbols,
	lto_symtab_prevailing_decl): MOve to lto-symtab.h.
	* lto-streamer-out.c (DFS::DFS_write_tree_body): Check that
	DECL_ABSTRACT_ORIGIN is not error_mark_node.

	* lto-symtab.c: Include lto-symtab.h.
	(lto_cgraph_replace_node): Do not merge profiles here.
	(lto_symtab_merge_p): New function.
	(lto_symtab_merge_decls_2): Honor lto_symtab_merge_p.
	(lto_symtab_merge_symbols_1): Turn unmerged decls into transparent
	aliases.
	(lto_symtab_merge_symbols): Do not clear node->aux; we no longer use it.
	(lto_symtab_prevailing_decl): Move to lto-symtab.h; rewrite.
	* lto.c: Include lto-symtab.h
	* lto-symtab.h: New.

From-SVN: r231438