ci: archive build logs on failure

ci/Jenkinsfile

@@ -29,5 +29,10 @@ pipeline {
                 archiveArtifacts '*'
             }
         }
+        failure {
+            dir('/var/tmp/portage') {
+                archiveArtifacts '*/*/temp/*.log'
+            }
+        }
     }
 }

ci/podTemplate.yaml

@@ -31,6 +31,9 @@ spec:
       subPath: distfiles
     - mountPath: /var/db/repos/gentoo
       name: portage
+    - mountPath: /var/tmp
+      name: workspace-volume
+      subPath: tmp
   hostUsers: false
   volumes:
   - name: binpkgs