Fix docker --init with /dev bind mount
Fix docker --init with /dev bind mount

In case a user wants to have a child reaper inside a container
(i.e. run "docker --init") AND a bind-mounted /dev, the following
error occurs:

> docker run -d -v /dev:/dev --init busybox top
> 088c96808c683077f04c4cc2711fddefe1f5970afc085d59e0baae779745a7cf
> docker: Error response from daemon: OCI runtime create failed: container_linux.go:296: starting container process caused "exec: "/dev/init": stat /dev/init: no such file or directory": unknown.

This happens because if a user-suppled /dev is provided, all the
built-in /dev/xxx mounts are filtered out.

To solve, let's move in-container init to /sbin, as the chance that
/sbin will be bind-mounted to a container is smaller than that for /dev.
While at it, let's give it more unique name (docker-init).

NOTE it still won't work for the case of bind-mounted /sbin.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

ibuildthecloud/docker,djs55/docker,YuPengZTE/docker,nalind/docker,mahak/docker,KarthikNayak/docker,paralin/docker,scotttlin/docker,scotttlin/docker,jimjag/docker,moby/moby,nawawi/docker,cpuguy83/docker,ibuildthecloud/docker,moul/docker,yosifkit/docker,AkihiroSuda/docker,jimjag/docker,paralin/docker,mahak/docker,flavio/docker,moby/moby,gnailuy/docker,dims/docker,flavio/docker,laijs/moby,dmcgowan/docker,docker/docker,jvanz/docker,jthelin/docker,trebonian/docker,kolyshkin/moby,dims/docker,kojiromike/docker,bearstech/moby,pradipd/moby,Mokolea/docker,thaJeztah/docker,rancher/docker,estesp/docker,trebonian/docker,YuPengZTE/docker,jameszhan/docker,konstruktoid/docker-upstream,jwhonce/docker,mahak/docker,nalind/docker,rremer/moby,Ramzec/docker,estesp/docker,ibuildthecloud/docker,konstruktoid/docker-1,ibuildthecloud/docker,YuPengZTE/docker,yongtang/docker,AkihiroSuda/docker,vdemeester/docker,crosbymichael/docker,justincormack/docker,moby/moby,unclejack/docker,Mokolea/docker,Mokolea/docker,nalind/docker,dmcgowan/docker,ibuildthecloud/docker,unclejack/docker,Ramzec/docker,laijs/docker,trebonian/docker,Ramzec/docker,rremer/moby,scotttlin/docker,cpuguy83/docker,docker/docker,pradipd/moby,gnailuy/docker,SvenDowideit/docker,nalind/docker,nawawi/docker,estesp/docker,konstruktoid/docker-upstream,vdemeester/docker,jthelin/docker,maxamillion/docker,cpuguy83/docker,kolyshkin/docker,KarthikNayak/docker,tmp6154/docker,jvanz/docker,kojiromike/docker,yosifkit/docker,maxamillion/docker,justincormack/docker,x1022as/docker,bearstech/moby,yongtang/docker,jlhawn/docker,laijs/docker,nawawi/docker,kojiromike/docker,gnailuy/docker,jlhawn/docker,tmp6154/docker,yosifkit/docker,djs55/docker,tmp6154/docker,jimjag/docker,moul/docker,moul/docker,dmcgowan/docker,justincormack/docker,docker/docker,moul/docker,thaJeztah/docker,mikebrow/docker,vdemeester/docker,paralin/docker,mikebrow/docker,laijs/moby,crosbymichael/docker,Mokolea/docker,crosbymichael/docker,konstruktoid/docker-upstream,laijs/docker,x1022as/docker,laijs/moby,rremer/moby,SvenDowideit/docker,kolyshkin/docker,unclejack/docker,jwhonce/docker,jameszhan/docker,AkihiroSuda/docker,pradipd/moby,nawawi/docker,bearstech/moby,rancher/docker,rancher/docker,jlhawn/docker,moby/moby,thaJeztah/docker,x1022as/docker,yongtang/docker,trebonian/docker,jimjag/docker,Ramzec/docker,gnailuy/docker,jwhonce/docker,yosifkit/docker,konstruktoid/docker-1,jameszhan/docker,flavio/docker,dims/docker,konstruktoid/docker-1,maxamillion/docker,KarthikNayak/docker,paralin/docker,djs55/docker,thaJeztah/docker,konstruktoid/docker-upstream,cpuguy83/docker,mahak/docker,kolyshkin/moby,kolyshkin/moby,SvenDowideit/docker,mikebrow/docker,flavio/docker,AkihiroSuda/docker,bearstech/moby,jvanz/docker