lologarithm: Ok, I figured out the cause and the fix! (In case anyone else has this problem)

Cause: Deleting/Renaming/Moving libstdc++.so.6 out of lin64 makes the game unable to update.

Solution (Run update with file existing):

1. Rename libstdc++.so.6 to something like libstdc++.so.6_backup
2. Launch game
3. Rename libstdc++.so.6 back to original name (without closing the game)
4. Go back to game and click update.
5. Patch will succeed, client will try to restart and crash (because you have libstdc++.so.6)
6. Hard close game, and delete/move libstdc++.so.6 again so that its no longer in lin64
7. Launch game again and it should be updated!