Add: run Clang 3.8 and commit-checker during CI (#6694)

Jenkinsfile

@@ -1,8 +1,16 @@
-def ci_targets = [
-    ["linux-amd64", "openttd/compile-farm-ci:linux-amd64"],
-    ["linux-i386", "openttd/compile-farm-ci:linux-i386"],
+def ci_checkers_targets = [
+    ["commit-checker", "openttd/compile-farm-ci:commit-checker"],
 ]
-def ci_stages = ci_targets.collectEntries {
+def ci_builds_targets = [
+    ["linux-amd64-clang-3.8", "openttd/compile-farm-ci:linux-amd64-clang-3.8"],
+    ["linux-amd64-gcc-6", "openttd/compile-farm-ci:linux-amd64-gcc-6"],
+    ["linux-i386-gcc-6", "openttd/compile-farm-ci:linux-i386-gcc-6"],
+]
+
+def ci_checkers_stages = ci_checkers_targets.collectEntries {
+    ["${it[0]}" : generateCI(it[0], it[1])]
+}
+def ci_builds_stages = ci_builds_targets.collectEntries {
     ["${it[0]}" : generateCI(it[0], it[1])]
 }
 
@@ -10,6 +18,7 @@ def generateCI(display_name, image_name) {
     return {
         dir("${display_name}") {
             unstash "source"
+
             docker.image("${image_name}").withRun("--volumes-from ${hostname} --workdir " + pwd()) { c->
                 sh "docker logs --follow ${c.id}"
                 sh "exit `docker wait ${c.id}`"
@@ -21,11 +30,19 @@ def generateCI(display_name, image_name) {
 node {
     stage("Checkout") {
         checkout scm
+
+        // Ensure we also have origin/master available
+        sh "git fetch --no-tags origin master:refs/remotes/origin/master"
+
         stash name: "source", useDefaultExcludes: false
     }
 
-    stage("CI") {
-        parallel ci_stages
+    stage("Checkers") {
+        parallel ci_checkers_stages
+    }
+
+    stage("Builds") {
+        parallel ci_builds_stages
     }
 }