ttyd: init at 1.4.2_pre174_6df6ac3e

ttyd hasn't seen a release in a while, but has a few useful bugfixes and
features (such as IPv6) that are good to have. It also seems to fix a
few crashes I encountered (likely due to newer openssl/libwebsockets).
So in an untraditional fashion, we'll adopt this with a _pre tag to
ensure it gets bumped correctly later on.

Signed-off-by: Austin Seipp <aseipp@pobox.com>