drm_hwcomposer: CI: Initial build and clang-tidy checks

Build android-agnostic code in linux environment.
Enable static code analysis using clang-tidy.

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
diff --git a/.ci/.gitlab-ci-checkcommit.sh b/.ci/.gitlab-ci-checkcommit.sh
new file mode 100755
index 0000000..314238f
--- /dev/null
+++ b/.ci/.gitlab-ci-checkcommit.sh
@@ -0,0 +1,58 @@
+#! /usr/bin/env bash
+
+echoerr() {
+	printf "ERROR: %s\n" "$*" >&2
+}
+
+findtag() {
+	local commit_body tag person
+	commit_body=$1
+	tag=$2
+	person=$3
+
+	# trim duplicate spaces from commit body and person
+	match="$tag: $(echo $person | tr -s ' ')"
+
+	if [ -z "$(echo "$commit_body" | tr -s ' ' | grep -i "$match")" ]; then
+		echoerr "Tag is missing from commit body"
+		echoerr ""
+		echoerr "Looking for '"$match"' in: "
+		echoerr "-----------------------------------------------------"
+		echoerr "$commit_body"
+		echoerr "-----------------------------------------------------"
+		echoerr ""
+		return 0
+	fi
+
+	return 1
+}
+
+git fetch https://gitlab.freedesktop.org/drm-hwcomposer/drm-hwcomposer.git
+
+git log --pretty='%h' FETCH_HEAD..HEAD | while read h; do
+	subject=$(git show -s --pretty='%s' "$h")
+	if [[ $subject != drm_hwcomposer:* ]]; then
+		echoerr "Invalid subject prefix: $subject"
+		exit 1
+	fi
+
+	commit_body=$(git show -s --pretty=%b "$h")
+
+	author=$(git show -s --format='%an <%ae>' "$h")
+	if findtag "$commit_body" "Signed-off-by" "$author"; then
+		echoerr "Author SoB tag is missing from commit $h"
+		exit 1
+	fi
+
+	committer=$(git show -s --format='%cn <%ce>' "$h")
+	if findtag "$commit_body" "Signed-off-by" "$committer"; then
+		echoerr "Committer SoB tag is missing from commit $h"
+		exit 1
+	fi
+
+	git show "$h" -- | clang-format-diff-11 -p 1 -style=file > /tmp/format-fixup.patch
+	if [ -s  /tmp/format-fixup.patch ]; then
+		cat /tmp/format-fixup.patch >&2
+		exit 1
+	fi
+done