ctdb debug vasprintf memory overwrite in ib

[tridge at samba.org]

James,

 > Note that you can't rely on this returning the number of characters  
 > that would have been output if the buffer were large enough until C99  
 > or UNIX98 IIRC.

lib/replace will replace vsnprintf() if it isn't C99 compliant. 

But I also think that the original vasprintf() code is fine. I think
Peter is seeing a bug from somewhere else.

Cheers, Tridge