gitlab: Wait for docker server to start

Should fix failures such as

$ docker info
Client:
 Debug Mode: false
Server:
ERROR: Cannot connect to the Docker daemon at unix:///var/run/docker.sock.
Is the docker daemon running?

Signed-off-by: Camilla Conte <cconte@redhat.com>
[rth: Split out of a larger patch]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

.gitlab-ci.d/container-template.yml

@@ -8,7 +8,7 @@
     - export TAG="$CI_REGISTRY_IMAGE/qemu/$NAME:latest"
     - export COMMON_TAG="$CI_REGISTRY/qemu-project/qemu/qemu/$NAME:latest"
     - apk add python3
-    - docker info
+    - until docker info; do sleep 1; done
     - docker login $CI_REGISTRY -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD"
   script:
     - echo "TAG:$TAG"

.gitlab-ci.d/opensbi.yml

@@ -53,6 +53,7 @@ docker-opensbi:
     DOCKER_TLS_CERTDIR: ""
   before_script:
     - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+    - until docker info; do sleep 1; done
   script:
     - docker pull $IMAGE_TAG || true
     - docker build --cache-from $IMAGE_TAG --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA