Generate a reverse dependency file for "gitlab-deps server"

The server needs the reverse dependency graph, make sure the
update-gitlab-deps script generates it as well.

contrib/start-server.sh

 #!/bin/sh
 
-deps_file=/var/lib/gitlab-deps/deps.list
+rev_deps_file=/var/lib/gitlab-deps/reverse-deps.list
 
 if [ -z "$GITLAB_URL" ]; then
     echo "Gitlab-deps is not configured (GITLAB_URL empty)" >&2
     exit 0
 fi
 
-if [ ! -e $deps_file ]; then
-    echo "No deps.json file, executing update..." >&2
+if [ ! -e $rev_deps_file ]; then
+    echo "No reverse-deps.list file, executing update..." >&2
     /usr/sbin/update-gitlab-deps --no-reload
     if [ $? -gt 0 ]; then
         echo "update-gitlab-deps failed" >&2
@@ -20,4 +20,4 @@ exec /usr/bin/gitlab-deps server \
      --token-file=$GITLAB_TOKEN_FILE --url=$GITLAB_URL \
      --addr=${ADDR:-0.0.0.0} --port=${PORT:-3535} \
      --webhook-auth-token=$WEBHOOK_AUTH_TOKEN \
-     < $deps_file
+     < $rev_deps_file

contrib/update.sh

 #!/bin/sh
 
 deps_file=/var/lib/gitlab-deps/deps.list
+rev_deps_file=/var/lib/gitlab-deps/reverse-deps.list
 reload=1
 ret=0
 
@@ -25,8 +26,9 @@ gitlab-deps list-projects $opts \
     | gitlab-deps deps $opts \
                   > $tmp_file
 
-if ! cmp $tmp_file $deps_file; then
+if ! cmp --quiet $tmp_file $deps_file; then
     mv -f $tmp_file $deps_file
+    awk '{print $2, $1}' < $deps_file > $rev_deps_file
     if [ $reload -eq 1 ]; then
         systemctl reload-or-restart gitlab-deps
         ret=$?