xwayland: Clean up pending eglstream on pixmap destroy
EGLStream implementation in Xwayland keeps a list of pending streams for a window.
If the windows's pixmap is destroyed while there is a pending stream, the pending stream will point to freed memory once the callback is triggered.
Make sure to cancel the pending stream if there's one when the pixmap is destroyed.
Signed-off-by: Olivier Fourdan ofourdan@redhat.com #1096 (closed)