The serial in wl_pointer.set_cursor must exactly match the one from
wl_pointer.enter, it should not use whatever serial for any input class
is the newest.
pass window and buffer index to buffer_release listener, so that it
fetches actual pointer to released buffer by wayland, instead of
directly passing a pointer to the UwacBuffer, which could result in
heap-use-after-free
`UwacWindowShmAllocBuffers()` allocates memory with `mmap` and never frees it
resulting in SIGBUS errors and running out of memory after some time.
Adding a corresponding `munmap` fixes this issue.
* Buffer submit now ignores duplicate buffer submit again.
* Frame callback is cleaned up in the callback function now.
* Damage region is currently ignored as there are screen artifacts otherwise.
