With this change, all ChangeLog entries going forward are generated
into a file named ChangeLog in each distribution tarball.
ChangeLog entries prior to today's date are in ChangeLog-2011.
* Makefile.am (gen-ChangeLog): New rule.
(dist-hook): Depend on it.
(EXTRA_DIST): Add ChangeLog-2011.
* ChangeLog-2011: Renamed from ChangeLog
* ChangeLog: Remove file.
* .gitignore: Ignore ChangeLog.
* bootstrap.conf: Ensure that ChangeLog exists.
(gnulib_modules): Add gitlog-to-changelog.