maint: support amending the generated ChangeLog, and fix a typo
* Makefile.am (gitlog_to_changelog_options): Add support for
amending the generated ChangeLog.
(EXTRA_DIST): Update.
* .git-log-fix: New file with things to amend to the generated
ChangeLog, starting with a fix for a typo in v1.11-1963-g3b369e6
"maint: use AC_PACKAGE_BUGREPORT to avoid duplication" from
yesterday.