package: move skeletons into data/skeletons

* data/bison.m4, data/c++-skel.m4, data/c++.m4, data/c-like.m4,
* data/c-skel.m4, data/c.m4, data/d-skel.m4, data/d.m4, data/glr.c,
* data/glr.cc, data/java-skel.m4, data/java.m4, data/lalr1.cc,
* data/lalr1.d, data/lalr1.java, data/location.cc, data/stack.hh,
* data/variant.hh, data/yacc.c:
Move to...
* data/skeletons: here.
Use b4_skeletonsdir instead of b4_pkgdatadir.

* data/local.mk, src/output.c: Adjust.

data/skeletons/stack.hh

@@ -0,0 +1,164 @@
+# C++ skeleton for Bison
+
+# Copyright (C) 2002-2015, 2018 Free Software Foundation, Inc.
+
+# This program 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 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+# b4_stack_file
+# -------------
+# Name of the file containing the stack class, if we want this file.
+b4_defines_if([b4_required_version_if([302], [],
+                                      [m4_define([b4_stack_file], [stack.hh])])])
+
+
+# b4_stack_define
+# ---------------
+m4_define([b4_stack_define],
+[[  /// A stack with random access from its top.
+  template <typename T, typename S = std::vector<T> >
+  class stack
+  {
+  public:
+    // Hide our reversed order.
+    typedef typename S::reverse_iterator iterator;
+    typedef typename S::const_reverse_iterator const_iterator;
+    typedef typename S::size_type size_type;
+
+    stack (size_type n = 200)
+      : seq_ (n)
+    {}
+
+    /// Random access.
+    ///
+    /// Index 0 returns the topmost element.
+    T&
+    operator[] (size_type i)
+    {
+      return seq_[size () - 1 - i];
+    }
+
+    /// Random access.
+    ///
+    /// Index 0 returns the topmost element.
+    T&
+    operator[] (int i)
+    {
+      return operator[] (size_type (i));
+    }
+
+    /// Random access.
+    ///
+    /// Index 0 returns the topmost element.
+    const T&
+    operator[] (size_type i) const
+    {
+      return seq_[size () - 1 - i];
+    }
+
+    /// Random access.
+    ///
+    /// Index 0 returns the topmost element.
+    const T&
+    operator[] (int i) const
+    {
+      return operator[] (size_type (i));
+    }
+
+    /// Steal the contents of \a t.
+    ///
+    /// Close to move-semantics.
+    void
+    push (YY_MOVE_REF (T) t)
+    {
+      seq_.push_back (T ());
+      operator[](0).move (t);
+    }
+
+    /// Pop elements from the stack.
+    void
+    pop (int n = 1) YY_NOEXCEPT
+    {
+      for (; 0 < n; --n)
+        seq_.pop_back ();
+    }
+
+    /// Pop all elements from the stack.
+    void
+    clear () YY_NOEXCEPT
+    {
+      seq_.clear ();
+    }
+
+    /// Number of elements on the stack.
+    size_type
+    size () const YY_NOEXCEPT
+    {
+      return seq_.size ();
+    }
+
+    /// Iterator on top of the stack (going downwards).
+    const_iterator
+    begin () const YY_NOEXCEPT
+    {
+      return seq_.rbegin ();
+    }
+
+    /// Bottom of the stack.
+    const_iterator
+    end () const YY_NOEXCEPT
+    {
+      return seq_.rend ();
+    }
+
+  private:
+    stack (const stack&);
+    stack& operator= (const stack&);
+    /// The wrapped container.
+    S seq_;
+  };
+
+  /// Present a slice of the top of a stack.
+  template <typename T, typename S = stack<T> >
+  class slice
+  {
+  public:
+    slice (const S& stack, int range)
+      : stack_ (stack)
+      , range_ (range)
+    {}
+
+    const T&
+    operator[] (int i) const
+    {
+      return stack_[range_ - i];
+    }
+
+  private:
+    const S& stack_;
+    int range_;
+  };
+]])
+
+m4_ifdef([b4_stack_file],
+[b4_output_begin([b4_dir_prefix], [b4_stack_file])[
+]b4_generated_by[
+// Starting with Bison 3.2, this file is useless: the structure it
+// used to define is now defined with the parser itself.
+//
+// To get rid of this file:
+// 1. add 'require "3.2"' (or newer) to your grammar file
+// 2. remove references to this file from your build system.
+]b4_output_end[
+]])