Build info documentation. Some code borrowed from Automake.
* configure.ac: Check for makeinfo.
* Makefile.in (MAKEINFO, INFOS, info_INFOS): New variables.
(MAINTAINER_CLEANFILES): Add $(INFOS), docs/stamp-vti, and
docs/version.texi.
(MOSTLYCLEANFILES): Add vti.tmp.
(docs/version.texi, docs/stamp-vti): Update automatically.
(docs/grub.info): Build info documentation. Use --force and ignore
errors for now.
(all-local): Add $(INFOS).
(install-local): Install info files.
(uninstall): Uninstall info files.
* docs/version.texi: Remove from revision control. This file is
automatically generated on build now.
* gendistlist.sh: Add `*.info'.