Do not hard code values of directories in `configure.in'.

Do not hard code values of directories in `configure.in'.
Update the `configure' tool chain.

* configure.in (XPFILE, XPFILE1, LOCALEDIR): Remove, handled by
src/makefile.am.
(VERSION_STRING): Use the third arg of AC_DEFINE_UNQUOTED.
(AC_OUTPUT): Add m4/Makefile.
Bump to bison 1.28a, 1.29 has never been released.
* acconfig.h (XPFILE, XPFILE1, LOCALEDIR): Remove, since they are
handled via src/Makefile.am.
(VERSION_STRING, PROTOTYPES, ENABLE_NLS, HAVE_CATGETS,
HAVE_GETTEXT, HAVE_LC_MESSAGES, HAVE_STPCPY): Remove, handled by
autoheader.
* Makefile.am (SUBDIRS): Add m4.
(ACLOCAL_AM_FLAGS): New variable.
(AUTOMAKE_OPTIONS): Add check-news.
* src/Makefile.am (bison.simple): Use awk to replace #line lines with
the proper line number and file name.
(DEFS): Propagate the location of bison library files and of the
locale files.
(INCLUDES): Added `-I ..' so that one can compile with srcdir !=
builddir.
* acinclude.m4: Remove, replaced by the directory m4.
* m4/Makefile.am (EXTRA_DIST): New variable.
* m4/gettext.m4: New file, from the fileutils.
* m4/lcmessage.m4: Likewise
* m4/progtest.m4: Likewise.
* m4/bison-decl.m4: New file, extracted from former acinclude.m4.