[gnugo-devel] unused_1_27.1

[Daniel Bump]

Trevor suggested (prompted by another suggestion of David,
who originally came up with the x=x definition of UNUSED,
many ages ago) that UNUSED x be defined as (void)x.

The purpose of this definition is to prevent the compiler
from issuing a warning if a function parameter isn't used.
It works on Linux, and is surely better than the old
definition, so I added it to the CVS. 

Let us know if it causes warnings on any platforms.

Dan