re PR c++/57038 (Latest libreoffice compilation fails with enabled LTO)
PR lto/57038
PR lto/47375
* lto-symtab.c (lto_symtab_symbol_p): Add external symbol; weakrefs are
not external.
(lto_symtab_merge_decls): Fix thinko when dealing with non-lto_symtab decls.
(lto_symtab_merge_cgraph_nodes): Use lto_symtab_symbol_p.
(lto_symtab_prevailing_decl): Get int sync with lto_symtab_symbol_p.
* varpool.c (dump_varpool_node): Dump more flags.