[mutter] ci: Blacklist .c and .h in the commit message subject prefix

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 72aeeb8c378836f7eb6132bafe83354eb6a8963a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Apr 2 10:47:06 2019 +0200

    ci: Blacklist .c and .h in the commit message subject prefix
    
    `boxes.c: Do that` should be just `boxes: Do that`.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/519

 .gitlab-ci/check-commit-log.sh | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/.gitlab-ci/check-commit-log.sh b/.gitlab-ci/check-commit-log.sh
index b5e7bae08..ae696eb8b 100755
--- a/.gitlab-ci/check-commit-log.sh
+++ b/.gitlab-ci/check-commit-log.sh
@@ -32,6 +32,11 @@ function commit_message_subject_is_compliant() {
     return 1
   fi
 
+  if echo "$commit_message_subject" | grep -qe "\.[ch]:"; then
+    echo " - message subject prefix should not include .c, .h, etc."
+    return 1
+  fi
+
   return 0
 }