lto-plugin.c: Include <hashtab.h>

* lto-plugin.c: Include <hashtab.h>
        (sym_aux): Add next_conflict field to save conflict chains.
        (plugin_file_info): Add conflicts symtab.
        (parse_table_entry): Initialize aux->next_conflict.
        (process_symtab): Increment found.
        (dump_symtab): Add.
        (finish_conflict_resolution): Add.
        (free_symtab): Add.
        (write_resolution): Remove symbols loop and move into
        dump_symtab. Call dump_symtab for main symbol and conflicts table.
        Call free_symtab to free conflicts table.
        (SWAP): Add.
        (eq_sym): Add.
        (hash_sym): Add.
        (symbol_strength): Add.
        (resolve_conflicts): Add.
        (claim_file_handler): Add n variable. Check return value of
        process_symtab. Call resolve_conflicts.

From-SVN: r162915