tools: Use topological commit ordering when generating ChangeLog files

This means that commits from the same merge request will always appear
together in the ChangeLog, instead of appearing shuffled together with
other commits that were authored around the same time.

tools/create-changelog.sh

@@ -4,7 +4,8 @@
 #
 # License: GPL-3.0+
 
-git log --date=iso8601 --no-decorate --abbrev=12 1.0.28..HEAD \
+git log --date=iso8601 --no-decorate --topo-order --abbrev=12 \
+        1.0.28..HEAD \
     | sed 's/[[:space:]]*$//' \
     > ChangeLog