travis-ci: add static analysis build job to run coccicheck

Add a dedicated build job for static analysis. As a starter we only run
coccicheck but in the future we could run Clang Static Analyzer or
similar tools, too.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.travis.yml

@@ -60,6 +60,18 @@ matrix:
         # Use the following command to debug the docker build locally:
         # $ docker run -itv "${PWD}:/usr/src/git" --entrypoint /bin/bash daald/ubuntu32:xenial
         # root@container:/# /usr/src/git/ci/run-linux32-build.sh
+    - env: Static Analysis
+      os: linux
+      compiler:
+      addons:
+        apt:
+          packages:
+          - coccinelle
+      before_install:
+      script:
+        # "before_script" that builds Git is inherited from base job
+        - make coccicheck
+      after_failure:
     - env: Documentation
       os: linux
       compiler: clang