Free str after using it in the version method. Use sudo_conv, not

io_conv since we don't have the IO conversation function pointer
in the I/O version method anymore now that io_open is delayed.

plugins/sudoers/sudoers.c

@@ -1110,6 +1110,7 @@ sudoers_policy_version(int verbose)
     msg.msg = str;
     memset(&repl, 0, sizeof(repl));
     sudo_conv(1, &msg, &repl);
+    free(str);
 
 #ifdef notyet
     if (verbose) {