CI: do the rebuilds via kaniko.

1 job from ci-changes in 16 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #241201
build

00:00:16

 
Name Stage Failure
failed
build Build There has been a runner system failure, please try again
Using docker image sha256:3b930f90663c1853824e789aacd53a763700d849d59c95bcfc4e93d243e015b0 for registry.videolan.org:5000/videolan-kaniko-aarch64:20181206200845 ...
Running on runner-d04e61d4-project-343-concurrent-0 via kidd...
Fetching changes...
HEAD is now at bc1299f Added kaniko.
From https://code.videolan.org/videolan/docker-images-aarch64
+ d1a376e...5d3265e ci-changes -> origin/ci-changes (forced update)
Checking out 5d3265e6 as ci-changes...
Skipping Git submodules setup
ERROR: Job failed (system failure): Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "exec: \"sh\": executable file not found in $PATH": unknown (executor_docker.go:1013:1s)