gitlab: create an explicit stage for cross build jobs

As we introduce more build jobs, it will be useful to have a grouping of
jobs to more easily visualize the results and potentially control build
ordering.
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

.gitlab-ci.yml

@@ -2,7 +2,12 @@ variables:
   MAKE: make
   GIT_DEPTH: 100
 
-.job_template: &job_definition
+stages:
+  - cross_build
+
+
+.cross_build_default_job_template: &cross_build_default_job_definition
+  stage: cross_build
   script:
     - mkdir build
     - cd build
@@ -14,37 +19,37 @@ variables:
 # to achieve reasonable cross-coverage.
 
 debian-9-cross-armv6l:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-9-cross-armv6l:latest
 
 debian-9-cross-mips64el:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-9-cross-mips64el:latest
 
 debian-9-cross-mips:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-9-cross-mips:latest
 
 debian-10-cross-aarch64:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-10-cross-aarch64:latest
 
 debian-10-cross-ppc64le:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-10-cross-ppc64le:latest
 
 debian-10-cross-s390x:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-10-cross-s390x:latest
 
 debian-sid-cross-armv7l:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-sid-cross-armv7l:latest
 
 debian-sid-cross-i686:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-sid-cross-i686:latest
 
 debian-sid-cross-mipsel:
-  <<: *job_definition
+  <<: *cross_build_default_job_definition
   image: quay.io/libvirt/buildenv-libvirt-debian-sid-cross-mipsel:latest