Add review stage to the CI checking formatting

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

.gitlab-ci/clang-format-check.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+# Based on Github Action
+# https://github.com/yshui/git-clang-format-lint
+
+diff=`git-clang-format --diff --commit $CI_MERGE_REQUEST_DIFF_BASE_SHA`
+[ "$diff" = "no modified files to format" ] && exit 0
+[ "$diff" = "clang-format did not modify any files" ] && exit 0
+
+printf "You have introduced coding style breakages, suggested changes:\n\n"
+
+echo "$diff" | colordiff
+exit 1