support/misc/gitlab-ci.yml.in: pass emulator builtin binaries as artifacts

Notes: We can't use runtime_test_download job from the parent pipeline
(generate-gitlab-ci) since the artifacts archive size is limited to 5MB.
So introduce a new custom stage named "download" executed before "test"
stage. test-dl directory that contain downloaded files can be an
artifact of the job passed to all jobs of next stages.

Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/4409032417

Runtime tested:
https://gitlab.com/kubu93/buildroot/-/pipelines/934319226

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

support/misc/gitlab-ci.yml.in

@@ -1,4 +1,5 @@
 stages:
+  - download
   - test
 
 before_script:
@@ -78,6 +79,16 @@ before_script:
             - output/build/*/.config
             - runtime-test.log
 
+.runtime_test_download:
+    stage: download
+    # Keep test-dl directory so the downloaded files can be an artifact of
+    # the job passed to all jobs of next stages.
+    script: ./support/testing/run-tests -d test-dl/ --prepare-only
+    artifacts:
+        when: always
+        paths:
+            - test-dl/
+
 .runtime_test_base:
     stage: test
     # Keep build directories so the rootfs can be an artifact of the job. The

support/scripts/generate-gitlab-ci-yml

@@ -132,6 +132,7 @@ gen_tests() {
     fi
 
     if ${do_runtime:-false}; then
+        printf 'runtime_test_download: { extends: .runtime_test_download }\n'
         printf '%s: { extends: .runtime_test_base }\n' "${runtimes[@]}"
     fi