xcb-client-helper: Call xcb_wait_for_event directly

We're currently calling ppoll() before calling xcb_wait_for_event(), which
may be due to initially trying to make this non-blocking.

However, xcb_wait_for_event() reads all events available - even if there
are more than one.

There are a handful of X properties we're sent that we don't explicitly
ask for, and if these end up in the same read, we could theoretically
end up in a poll() with nothing coming in.

Drop the extra ppoll() and just let xcb_wait_for_event() do the blocking
for us.

I'm hoping this fixes the occasional timeout in the xwayland test, but
it's a reasonable code simplification even if it doesn't.

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>

tests/xcb-client-helper.c

@@ -380,23 +380,6 @@ window_x11_unmap(struct window_x11 *window)
 	xcb_flush(window->conn->connection);
 }
 
-static xcb_generic_event_t *
-poll_for_event(xcb_connection_t *conn)
-{
-	int fd = xcb_get_file_descriptor(conn);
-	struct pollfd pollfds = {};
-	int rpol;
-
-	pollfds.fd = fd;
-	pollfds.events = POLLIN;
-
-	rpol = ppoll(&pollfds, 1, NULL, NULL);
-	if (rpol > 0 && (pollfds.revents & POLLIN))
-		return xcb_wait_for_event(conn);
-
-	return NULL;
-}
-
 static void
 window_x11_set_cursor(struct window_x11 *window, const char *cursor_name)
 {
@@ -478,7 +461,7 @@ handle_events_x11(struct window_x11 *window)
 			break;
 		}
 
-		ev = poll_for_event(window->conn->connection);
+		ev = xcb_wait_for_event(window->conn->connection);
 		if (!ev) {
 			fprintf(stderr, "Error, no event received, "
 					"although we requested for one!\n");