[krbdev.mit.edu #6090] k5_mutex_destroy calls pthread_mutex_destroy with mutex locked

[Ezra Peisach via RT]

Ken Raeburn via RT wrote:
>
> (Weirdly enough, though, the build *stopped* failing when we fixed a  
> bug in the snapshot process and started testing today's code instead  
> of something from last month.  I'm not sure what's up with that.)
>
>   
You did turn off thread debugging recently... Maybe that was related....
> Ken
>
>