This partially reverts e0b59ab52b,
and does not automatically disable proxying signals in TTY-mode
Before this change:
------------------------------------
Start a container with a TTY in one shell:
```
docker run -it --init --name repro-28872 busybox sleep 30
```
then, in another shell, kill the docker cli:
```
kill `pgrep -f repro-28872`
```
Notice that the CLI was killed, but the signal not forwarded to the container;
the container continues running
```
docker container inspect --format '{{ .State.Status }}' repro-28872
running
docker container rm -f repro-28872
```
After this change:
------------------------------------
Start a container with a TTY in one shell:
```
docker run -it --init --name repro-28872 busybox sleep 30
```
then, in another shell, kill the docker cli:
```
kill `pgrep -f repro-28872`
```
Verify that the signal was forwarded to the container, and the container exited
```
docker container inspect --format '{{ .State.Status }}' repro-28872
exited
docker container rm -f repro-28872
```
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
ee29504923