Fix more warning-addition fallout

I'm normally a big fan of small atomic commits, but I also want to get
things done this afternoon...

Bug: https://bugzilla.gnome.org/show_bug.cgi?id=687441
Reviewed-by: Colin Walters <walters@verbum.org>

tests/iochannel-test.c

@@ -15,7 +15,7 @@ static void
 test_small_writes (void)
 {
   GIOChannel *io;
-  GIOStatus status;
+  GIOStatus status = G_IO_STATUS_ERROR;
   guint cnt; 
   gchar tmp;
   GError *error = NULL;