This patch continues runtime removal by moving the tty implementations
into `sys`.
Because this eliminates APIs in `libnative` and `librustrt`, it is a:
[breaking-change]
This functionality is likely to be available publicly, in some form,
from `std` in the future.
Spring cleaning is here! In the Fall! This commit removes quite a large amount
of deprecated functionality from the standard libraries. I tried to ensure that
only old deprecated functionality was removed.
This is removing lots and lots of deprecated features, so this is a breaking
change. Please consult the deprecation messages of the deleted code to see how
to migrate code forward if it still needs migration.
[breaking-change]
