* configure.ac: Use AC_CONFIG_AUX_DIR.  Remove args from
AM_INIT_AUTOMAKE.  Replace AM_CONFIG_HEADER by AC_CONFIG_HEADER.
* compile, config.guess, config.sub, depcomp, install-sh, ltmain.sh
* mkinstalldirs, texinfo.texi: Move to build-aux/ and update from
gnulib (c042abf).
* build-aux/mdate-sh, build-aux/missing: Install via automake -a -c.
Update autogen.sh for changed config dir.
* autogen.sh: Adjust for scripts dir change.  Update W32 toolprefix
list.