restore gosu suid bit when supervisor container stops

[kaluzki]

closes:

• #226
• #366

---

fixes:

• https://github.com/webdevops/Dockerfile/pull/333#issuecomment-615840529:

##
# interactive 'entrypoint.d/supervisord.sh' -> strg+c
##

$ docker run --name bug226 -ti -u 1000 webdevops/base:alpine
-> Executing /opt/docker/provision/entrypoint.d/05-gosu.sh
...
^C
Container stopped, performing teardown...
-> Executing /opt/docker/provision/entrypoint.d/teardown/05-gosu.sh

$ docker start bug226
bug226
$ docker logs bug226
...
INFO supervisord started
...


$ docker exec -ti bug226 whoami
whoami: unknown uid 1000

$ docker stop bug226 
$ docker rm bug226



##
# daemon 'entrypoint.d/supervisord.sh'
##

$ docker run --name bug226 -d --user 1000 webdevops/base:alpine
$ docker logs bug226
-> Executing /opt/docker/provision/entrypoint.d/05-gosu.sh
...
INFO supervisord started
...

$ docker exec -ti bug226 whoami
whoami: unknown uid 1000

$ docker stop bug226
$ docker logs bug226



##
# interactive 'entrypoint.d/default.sh' bash -> strg+d
##

$ docker run --rm -ti webdevops/base:alpine bash
bash-4.4
# exit