expireover core (perhaps an ov3search bug)

[Fletcher Mattox]

This is essentially the same stack trace I reported on Feb 29.
My overview file was definitely corrupted.  Actually it's fairly
reproducible.  Just send expireover a SIGTERM and wait for news.daily
to run.  Expireover segfaulted every night until I manually unlinked
the corrupt overview file.

> Running inn-CURRENT-20000411 with tradindexed. The overview file is possibly
> corrupted due to a system crash.
> 
> And here is the stack trace :
> 
> #0  0x804d171 in OVERGetHeader (
>     p=0x62ab6936 <Address 0x62ab6936 out of bounds>, field=3) at ov.c:946
> 946         for (; field-- >= 0 && *p; p++)
> (gdb) where
> #0  0x804d171 in OVERGetHeader (
>     p=0x62ab6936 <Address 0x62ab6936 out of bounds>, field=3) at ov.c:946
> #1  0x804d779 in OVhisthasmsgid (
>     data=0x62ab6936 <Address 0x62ab6936 out of bounds>) at ov.c:1138
> #2  0x805d265 in tradindexed_expiregroup (
>     group=0x8081004 "comp.infosystems.www.servers.ms-windows", lo=0xbfbfcea0)
>     at ov3.c:1109
> #3  0x804bfdf in OVexpiregroup (
>     group=0x8081004 "comp.infosystems.www.servers.ms-windows", lo=0xbfbfcea0)
>     at ov.c:357
> #4  0x8049c92 in main (argc=1, argv=0xbfbfef28) at expireover.c:140
> #5  0x8049741 in _start ()