gitlog-to-changelog: provide a ChangeLog-repair mechanism
Git logs are often treated as immutable, because editing them
changes the SHA1 checksums of all descendants. Thus, errors in
git logs tend to stay there forever. However, when we generate
a ChangeLog file -- typically for distribution -- from that git log,
we can actually make corrections in the generated file. The key
lies in recording in machine-readable/applicable form the desired
corrections. See --help for description and an example.
* build-aux/gitlog-to-changelog (parse_amend_file): New function.
(usage): Describe it; alphabetize option descriptions.
(main): Honor the new option, carefully.