includes: must not check *.hxx

* tests/sanity/includes.test: here.

tests/sanity/includes.test

 #! /bin/sh
 # -*- coding: utf-8 -*-
-# Copyright (C) 2008, 2011-2012, 2016, 2018-2019 Laboratoire de
+# Copyright (C) 2008, 2011-2012, 2016-2019 Laboratoire de
 # Recherche et Développement de l'Epita (LRDE).
 # Copyright (C) 2004, 2005 Laboratoire d'Informatique de Paris 6
 # (LIP6), département Systèmes Répartis Coopératifs (SRC), Université
@@ -48,6 +48,9 @@ for file in `find "$INCDIR" \( -name "${1-*}.hh" \
      continue
    fi
 
+   # If it is an hxx file the file may not be autocontaining
+   case $file in *.hxx ) continue ;; esac
+
    echo "#include <spot/$file>" >incltest.cc
    if $CXX $CPPFLAGS -DSKIP_DEPRECATED_WARNING $CXXFLAGS \
            -I$top_builddir -I$top_srcdir -I$top_srcdir/buddy/src \