tdesktop: Remove the last custom patch from Arch Linux

This patch is not required anymore [0][1].
Thanks @ilya-fedin for pointing this out.

[0]: https://git.archlinux.org/svntogit/community.git/commit/?id=a6dbffec8b2f6f319822df8b7db3ba66f81407ce
[1]: https://bugs.archlinux.org/task/65259