handle: Close logfd when handle is freed

As well as being tidy, this provides useful information
to the log receiving end that the handle is going away
as it will get EOF.

libknet/handle.c

@@ -792,6 +792,7 @@ int knet_handle_free(knet_handle_t knet_h)
 	crypto_fini(knet_h, KNET_MAX_CRYPTO_INSTANCES + 1); /* values above MAX_CRYPTO will release all crypto resources */
 	compress_fini(knet_h, 1);
 	_destroy_locks(knet_h);
+	close(knet_h->logfd);
 
 	free(knet_h);
 	knet_h = NULL;