Fix debugging reference from non-GSS to optional GSS code.

Fix debugging reference from non-GSS to optional GSS code.

From: Nick Alcock <nick.alcock@oracle.com>

AUTH_DESTROY() and auth_destroy() are pulling in log_debug() from
authgss_prot.c, but are used from outside the GSS code, thus preventing
libtirpc
from being used if compiled without GSS support.

The (somewhat ugly) fix here defines a new macro to do the job. Because
we're
not compiling as C99, I use the GNU C variadic macro extension: if we
mean to
be compiled with other compilers, this needs to change.

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>