Update configure.in; support both baz and tla; avoid using dirent.

configure.in: Remove AC_PROG_RANLIB since we never use ranlib.  Add
    AC_PROG_LIBTOOL since we do use libtool.  Set GNU_ARCH and
    HAS_GNU_ARCH based on whether the system has baz or tla.  Do not
    check for dirent.d_type.

src/Makefile.am: Make the "checkversion" target conditional on
    HAS_GNU_ARCH, and use the detected $(GNU_ARCH).

src/helpfile.c (language_read): Report error text when unable to open a
    language directory.
  (language_read_list): Always stat the language entry to determine
    whether it is a directory; Cygwin has no dirent.d_type and ReiserFS
    has a broken one.
git-archimport-id: srvx@srvx.net--2006/srvx--devo--1.3--patch-3