configure: remove useless calls to AC_CHECK_PROG

Fixes #329.

* configure.ac: Do not check for lbt, modella, and ltl2nba.
* bench/ltl2tgba/defs.in: Remove the associated substitutions,
not used in the scripts.

bench/ltl2tgba/defs.in

 # -*- mode: shell-script; coding: utf-8 -*-
-# Copyright (C) 2012, 2013, 2016 Laboratoire de Recherche et Développement
-# de l'Epita (LRDE).
+# Copyright (C) 2012, 2013, 2016, 2018 Laboratoire de Recherche et
+# Développement de l'Epita (LRDE).
 # Copyright (C) 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 # département Systèmes Répartis Coopératifs (SRC), Université Pierre
 # et Marie Curie.
@@ -35,17 +35,13 @@ test -f "$srcdir/defs.in" || {
 }
 
 top_builddir="@top_builddir@"
-LBT="@LBT@"
 LTLCROSS="$top_builddir/bin/ltlcross@EXEEXT@"
 LTLFILT="$top_builddir/bin/ltlfilt@EXEEXT@"
 RANDLTL="$top_builddir/bin/randltl@EXEEXT@"
 GENLTL="$top_builddir/bin/genltl@EXEEXT@"
 LTL2BA="@LTL2BA@"
 LTL3BA="@LTL3BA@"
-LTL2NBA="@LTL2NBA@"
 LTL2TGBA="@top_builddir@/bin/ltl2tgba@EXEEXT@"
-MODELLA="@MODELLA@"
 SPIN="@SPIN@"
-WRING2LBTT="@WRING2LBTT@"
 
 . ${TOOLS-$srcdir/tools}

configure.ac

@@ -171,11 +171,8 @@ fi
 
 AM_CONDITIONAL([NEVER], [false])
 AC_CHECK_PROG([DOT], [dot], [dot])
-AC_CHECK_PROG([LBT], [lbt], [lbt])
 AC_CHECK_PROG([LTL2BA], [ltl2ba], [ltl2ba])
 AC_CHECK_PROG([LTL3BA], [ltl3ba], [ltl3ba])
-AC_CHECK_PROG([MODELLA], [modella], [modella])
-AC_CHECK_PROG([LTL2NBA], [script4lbtt.py], [script4lbtt.py])
 AC_CHECK_PROG([PERL], [perl], [perl])
 AC_CHECK_PROG([SPIN], [spin], [spin])
 AC_CHECK_PROG([LBTT], [lbtt], [lbtt])
@@ -183,7 +180,6 @@ AC_CHECK_PROG([EMACS], [emacs], [emacs])
 AC_CHECK_PROGS([IPYTHON], [ipython3 ipython], [ipython])
 AC_CHECK_PROG([LBTT_TRANSLATE], [lbtt-translate], [lbtt-translate])
 AX_CHECK_VALGRIND
-AC_CHECK_PROG([WRING2LBTT], [wring2lbtt], [wring2lbtt])
 # Debian has a binary for SWIG 3.0 named swig3.0 and they kept swig as
 # an alias for swig-2.0.  Let's use the former when available.
 AC_CHECK_PROGS([SWIG], [swig3.0 swig], [swig])