Rename configure.in to configure.ac, twice

* configure.ac: Rename from configure.in.
* GUILE-VERSION: Update comments; nfc.
* HACKING: Likewise.

* guile-readline/configure.ac: Rename from guile-readline/configure.in.
* guile-readline/LIBGUILEREADLINE-VERSION: Update comments; nfc.

* libguile/__scm.h: Likewise.
* libguile/gen-scmconfig.c: Likewise.
* libguile/gen-scmconfig.h.in: Likewise.

guile-readline/configure.ac

@@ -0,0 +1,86 @@
+AC_PREREQ(2.50)
+
+dnl Don't use "echo -n", which is not portable (e.g., not available on
+dnl MacOS X).  Instead, use `patsubst' to remove the newline.
+AC_INIT(guile-readline,
+        patsubst(m4_esyscmd(. ../GUILE-VERSION && echo ${GUILE_VERSION}), [
+]),
+	[bug-guile@gnu.org])
+
+AC_CONFIG_AUX_DIR([.])
+AC_CONFIG_SRCDIR(readline.c)
+AC_CONFIG_HEADERS([guile-readline-config.h])
+AM_INIT_AUTOMAKE([foreign no-define])
+
+. $srcdir/../GUILE-VERSION
+
+AC_PROG_INSTALL
+AC_PROG_CC
+AC_LIBTOOL_WIN32_DLL
+AC_PROG_LIBTOOL
+
+dnl
+dnl Check for Winsock and other functionality on Win32 (*not* CygWin)
+dnl
+AC_CYGWIN
+AC_MINGW32
+EXTRA_DEFS=""
+if test "$MINGW32" = "yes" ; then
+    if test $enable_shared = yes ; then
+      EXTRA_DEFS="-DSCM_IMPORT"
+    fi
+fi
+AC_SUBST(EXTRA_DEFS)
+
+for termlib in ncurses curses termcap terminfo termlib ; do
+   AC_CHECK_LIB(${termlib}, tgoto,
+                [LIBS="-l${termlib} $LIBS"; break])
+done
+
+AC_CHECK_LIB(readline, readline)
+if test $ac_cv_lib_readline_readline = no; then
+  AC_MSG_WARN([libreadline was not found on your system.])
+fi
+
+AC_CHECK_FUNCS(siginterrupt rl_clear_signals rl_cleanup_after_signal)
+
+dnl Check for modern readline naming
+AC_CHECK_FUNCS(rl_filename_completion_function)
+
+dnl Check for rl_get_keymap.  We only use this for deciding whether to
+dnl install paren matching on the Guile command line (when using
+dnl readline for input), so it's completely optional.
+AC_CHECK_FUNCS(rl_get_keymap)
+
+AC_CACHE_CHECK([for rl_getc_function pointer in readline],
+		 ac_cv_var_rl_getc_function,
+		 [AC_TRY_LINK([
+#include <stdio.h>
+#include <readline/readline.h>],
+			      [printf ("%ld", (long) rl_getc_function)],
+			      [ac_cv_var_rl_getc_function=yes],
+			      [ac_cv_var_rl_getc_function=no])])
+if test "${ac_cv_var_rl_getc_function}" = "yes"; then
+  AC_DEFINE(HAVE_RL_GETC_FUNCTION, 1,
+    [Define if your readline library has the rl_getc_function variable.])
+fi
+
+if test $ac_cv_lib_readline_readline = yes \
+        -a $ac_cv_var_rl_getc_function = no; then
+  AC_MSG_WARN([*** libreadline is too old on your system.])
+  AC_MSG_WARN([*** You need readline version 2.1 or later.])
+fi
+
+AC_CHECK_FUNCS(strdup)
+
+. $srcdir/LIBGUILEREADLINE-VERSION
+AC_SUBST(LIBGUILEREADLINE_MAJOR)
+AC_SUBST(LIBGUILEREADLINE_INTERFACE_CURRENT)
+AC_SUBST(LIBGUILEREADLINE_INTERFACE_REVISION)
+AC_SUBST(LIBGUILEREADLINE_INTERFACE_AGE)
+AC_SUBST(LIBGUILEREADLINE_INTERFACE)
+
+AC_SUBST(GUILE_EFFECTIVE_VERSION)
+
+AC_CONFIG_FILES(Makefile ice-9/Makefile)
+AC_OUTPUT