xen: Fix inside_daemon beeing unused when libvirtd is disabled

The defined __sun is there, because inside_daemon is used in xenUnifiedOpen
if __sun is defined.

src/xen/xen_driver.c

@@ -70,7 +70,9 @@ static struct xenUnifiedDriver const * const drivers[XEN_UNIFIED_NR_DRIVERS] = {
 #endif
 };
 
+#if defined WITH_LIBVIRTD || defined __sun
 static int inside_daemon;
+#endif
 
 #define xenUnifiedError(code, ...)                                         \
         virReportErrorHelper(NULL, VIR_FROM_XEN, code, __FILE__,           \