PATCH: inn-2.4.2:art.c:ARTxrefslave() bug causes ARTpost() segfault

[Chris Caputo]

Repro:

   0) xrefslave be true
   1) active file reload (such as by startup or newgroup message)
   2) multi-group cancel control message received prior to any other
      multi-group message with a higher number of groups.

Crash due to segmentation fault at 2.4.2's art.c line 2296:

     ngp->PostCount = 0;

I believe fix to ARTxrefslave() is as follows.

Thanks,
Chris

--- inn-2.4.2-stock/innd/art.c  2004-12-22 04:21:19.000000000 +0000
+++ inn-2.4.2/innd/art.c        2005-07-02 14:25:32.000000000 +0000
@@ -1525,6 +1525,7 @@ ARTxrefslave(ARTDATA *data)
      GroupPointers[i++] = ngp;
      nogroup = false;
    }
+  GroupPointers[i] = NULL;
    if (nogroup)
      return false;
    return true;