[2/2] dtc: Move some functions to util.[ch]

[Jon Loeliger]

> Now that we have a util.[ch] file shared between dtc and
> convert-dtsv0, move some functions which are currently duplicated in
> the two to util files.  Specifically we move the die(), xmalloc() and
> xrealloc() functions.
> 
> While we're at it, add standard double-include protection to util.h
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

I would have sworn I applied this one earlier...
But now it definitely has been.

Thanks,
jdl