Add DCO check to kata-prechecks

Create pr-check pipeline that triggers on PR changes (not on
label changes). Add the dco-license job to the kata-prechecks
template.

Change-Id: Iffd6689a2edb95df7d0d4ec6b8e378fc0de20b08

zuul.d/pipelines.yaml

@@ -89,6 +89,40 @@
     window-floor: 20
     window-increase-factor: 2
 
+- pipeline:
+    name: pr-check
+    description: |
+      New PRs and modified PRs enter this pipeline to be tested.
+    success-message: DCO (Signed-Off-By) is present.
+    failure-message: Missing DCO (Signed-Off-By) in commit message.
+    manager: independent
+    precedence: low
+    trigger:
+      github:
+        - event: pull_request
+          action:
+            - opened
+            - changed
+            - reopened
+        - event: pull_request
+          action: comment
+          comment: (?i)^\s*/zuul-recheck\s*$
+    start:
+      github:
+        status: pending
+        comment: false
+    success:
+      github:
+        status: 'success'
+      mysql:
+    failure:
+      github:
+        status: 'failure'
+      mysql:
+    # Don't report merge-failures to github
+    merge-failure:
+      mysql:
+
 - pipeline:
     name: pr-status
     description: |

zuul.d/project-templates.yaml

@@ -3,6 +3,9 @@
     description: |
       This template contains pre-check tests for Kata containers
       repositories.
+    pr-check:
+      jobs:
+        - dco-license
     pr-status:
       jobs:
         - kata-github-wip