saveargs: let disasm do the lifting

@@ -42,10 +42,11 @@
     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;