core: re-run paint_preprocess after redirecting

paint_preprocess calls redir_start if it decides to redirect the screen.
redir_start might change the state of the windows. For example, when the
image of the window fails to bind, redir_start sets the error flag. And
those state changes might exclude the window from being rendered. Thus,
paint_preprocess should be re-run to make sure the new states are
honoured.

Fixes a crash when window images fail to bind after redirecting.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/win.c

@@ -196,7 +196,7 @@ _win_bind_image(session_t *ps, win *w, void **win_image, void **shadow_image) {
 	auto e = xcb_request_check(
 	    ps->c, xcb_composite_name_window_pixmap_checked(ps->c, w->id, pixmap));
 	if (e) {
-		log_error("Failed to get named pixmap");
+		log_error("Failed to get named pixmap for window %#010x(%s)", w->id, w->name);
 		free(e);
 		return false;
 	}