Remove useless forward declarations of class tgba.

* src/tgbaalgos/compsusp.hh, src/tgbaalgos/dotty.hh,
src/tgbaalgos/emptiness.hh, src/tgbaalgos/hoaf.hh,
src/tgbaalgos/neverclaim.hh, src/tgbaalgos/randomgraph.hh,
src/tgbaalgos/simulation.hh: Here.

src/tgbaalgos/compsusp.hh

 // -*- coding: utf-8 -*-
-// Copyright (C) 2012, 2013 Laboratoire de Recherche et Développement
-// de l'Epita (LRDE).
+// Copyright (C) 2012, 2013, 2014 Laboratoire de Recherche et
+// Développement de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
 //
@@ -25,7 +25,6 @@
 
 namespace spot
 {
-  class tgba;
   class bdd_dict;
 
   /// \brief Compositional translation algorithm with resetable

src/tgbaalgos/dotty.hh

@@ -29,7 +29,6 @@
 
 namespace spot
 {
-  class tgba;
   class dotty_decorator;
 
   /// \ingroup tgba_io

src/tgbaalgos/emptiness.hh

@@ -33,7 +33,6 @@
 
 namespace spot
 {
-  class tgba;
   struct tgba_run;
 
   /// \addtogroup emptiness_check Emptiness-checks

src/tgbaalgos/hoaf.hh

@@ -26,7 +26,6 @@
 
 namespace spot
 {
-  class tgba;
   enum hoaf_alias { Hoaf_Alias_None, Hoaf_Alias_Ap, Hoaf_Alias_Cond };
   enum hoaf_acceptance
     {

src/tgbaalgos/neverclaim.hh

@@ -29,8 +29,6 @@
 
 namespace spot
 {
-  class tgba;
-
   /// \ingroup tgba_io
   /// \brief Print reachable states in Spin never claim format.
   ///

src/tgbaalgos/randomgraph.hh

@@ -29,8 +29,6 @@
 
 namespace spot
 {
-  class tgba;
-
   /// \ingroup tgba_misc
   /// \brief Construct a tgba randomly.
   ///

src/tgbaalgos/simulation.hh

@@ -25,8 +25,6 @@
 
 namespace spot
 {
-  class tgba;
-
   /// \addtogroup tgba_reduction
   /// @{