saveargs: let disasm do the lifting

*** 42,51 ****
--- 42,52 ----
      global:
          dis_disassemble;
          dis_errno;
          dis_handle_create;
          dis_handle_destroy;
+         dis_instrlen;
          dis_max_instrlen;
          dis_previnstr;
          dis_set_data;
          dis_flags_set;
          dis_flags_clear;