bin: factor the calls to set_program_name().

* src/bin/common_setup.cc, src/bin/common_setup.hh: New files.
* src/bin/Makefile.am: Add them.
* src/bin/genltl.cc, src/bin/ltl2tgba.cc, src/bin/ltl2tgta.cc,
src/bin/ltlfilt.cc, src/bin/randltl.cc: Adjust.

src/bin/common_setup.cc

@@ -0,0 +1,31 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2012 Laboratoire de Recherche et Développement de
+// l'Epita (LRDE).
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// Spot is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+// or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+// License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Spot; see the file COPYING.  If not, write to the Free
+// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+
+#include "common_setup.hh"
+
+void
+setup(char** argv)
+{
+  // Simplify the program name, because argp() uses it to report
+  // errors and display help text.
+  set_program_name(argv[0]);
+  argv[0] = const_cast<char*>(program_name);
+}