gitlab: generate the gitlab-ci configuration before each build

Since Gitlab 12.9, Gitlab allow to trigger child pipeline with generated configuration file.
See: https://gitlab.com/gitlab-org/gitlab/-/issues/35632

This allow us to stop updating the .gitlab-ci.yml file when a
new defconfig is added to Buildroot.

Remove check-gitlab-ci.yml job since it is now uneeded.
Remove .gitlab-ci.yml make target.

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
[ann.morin.1998@free.fr: manual: no longer needed to update at all]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

support/misc/gitlab-ci.yml.in

@@ -0,0 +1,123 @@
+# Configuration for Gitlab-CI.
+# Builds appear on https://gitlab.com/buildroot.org/buildroot/pipelines
+
+image: buildroot/base:20191027.2027
+
+.check_base:
+    rules:
+        - if: '$CI_COMMIT_REF_NAME =~ /^.*-.*_defconfig$/ || $CI_COMMIT_REF_NAME =~ /^.*-tests\..*$/'
+          when: never
+        - when: always
+
+check-DEVELOPERS:
+    extends: .check_base
+    # get-developers should print just "No action specified"; if it prints
+    # anything else, it's a parse error.
+    # The initial ! is removed by YAML so we need to quote it.
+    script:
+        - "! utils/get-developers | grep -v 'No action specified'"
+
+check-flake8:
+    extends: .check_base
+    before_script:
+        # Help flake8 to find the Python files without .py extension.
+        - find * -type f -name '*.py' > files.txt
+        - find * -type f -print0 | xargs -0 file | grep 'Python script' | cut -d':' -f1 >> files.txt
+        - sort -u files.txt | tee files.processed
+    script:
+        - python -m flake8 --statistics --count --max-line-length=132 $(cat files.processed)
+    after_script:
+        - wc -l files.processed
+
+check-package:
+    extends: .check_base
+    script:
+        - make check-package
+
+.defconfig_base:
+    script:
+        - echo "Configure Buildroot for ${DEFCONFIG_NAME}"
+        - make ${DEFCONFIG_NAME}
+        - echo 'Build buildroot'
+        - |
+            make > >(tee build.log |grep '>>>') 2>&1 || {
+                echo 'Failed build last output'
+                tail -200 build.log
+                exit 1
+            }
+        - |
+            ./support/scripts/boot-qemu-image.py "${DEFCONFIG_NAME}" > >(tee runtime-test.log) 2>&1 || {
+                echo 'Failed runtime test last output'
+                tail -200 runtime-test.log
+                exit 1
+            }
+    artifacts:
+        when: always
+        expire_in: 2 weeks
+        paths:
+            - .config
+            - build.log
+            - output/images/
+            - output/build/build-time.log
+            - output/build/packages-file-list.txt
+            - output/build/*/.config
+            - runtime-test.log
+
+.defconfig:
+    extends: .defconfig_base
+    # Running the defconfigs for every push is too much, so limit to
+    # explicit triggers through the API.
+    rules:
+        # For tags, create a pipeline.
+        - if: '$CI_COMMIT_TAG'
+        # For pipeline created by using a trigger token.
+        - if: '$CI_PIPELINE_TRIGGERED'
+        # For the branch or tag name named *-defconfigs, create a pipeline.
+        - if: '$CI_COMMIT_REF_NAME =~ /^.*-defconfigs$/'
+    before_script:
+        - DEFCONFIG_NAME=${CI_JOB_NAME}
+
+one-defconfig:
+    extends: .defconfig_base
+    rules:
+        # For the branch or tag name named *-*_defconfigs, create a pipeline.
+        - if: '$CI_COMMIT_REF_NAME =~ /^.*-.*_defconfig$/'
+    before_script:
+        - DEFCONFIG_NAME=$(echo ${CI_COMMIT_REF_NAME} | sed -e 's,^.*-,,g')
+
+.runtime_test_base:
+    # Keep build directories so the rootfs can be an artifact of the job. The
+    # runner will clean up those files for us.
+    # Multiply every emulator timeout by 10 to avoid sporadic failures in
+    # elastic runners.
+    script:
+        - echo "Starting runtime test ${TEST_CASE_NAME}"
+        - ./support/testing/run-tests -o test-output/ -d test-dl/ -k --timeout-multiplier 10 ${TEST_CASE_NAME}
+    artifacts:
+        when: always
+        expire_in: 2 weeks
+        paths:
+            - test-output/*.log
+            - test-output/*/.config
+            - test-output/*/images/*
+
+.runtime_test:
+    extends: .runtime_test_base
+    # Running the runtime tests for every push is too much, so limit to
+    # explicit triggers through the API.
+    rules:
+        # For tags, create a pipeline.
+        - if: '$CI_COMMIT_TAG'
+        # For pipeline created by using a trigger token.
+        - if: '$CI_PIPELINE_TRIGGERED'
+        # For the branch or tag name named *-runtime-tests, create a pipeline.
+        - if: '$CI_COMMIT_REF_NAME =~ /^.*-runtime-tests$/'
+    before_script:
+        - TEST_CASE_NAME=${CI_JOB_NAME}
+
+one-runtime_test:
+    extends: .runtime_test_base
+    rules:
+        - if: '$CI_COMMIT_REF_NAME =~ /^.*-tests\..*$/'
+    before_script:
+        - TEST_CASE_NAME=$(echo ${CI_COMMIT_REF_NAME} | sed -e 's,^.*-,,g')