maint: de-recurse the handling of examples

The directory was still using a local Makefile.am because it provides
"scoped" Make variables: these examples are not meant to use the same
CPPFLAGS etc.  If we were to use the same -I set, we'd pick up
gnulib's stdio.h for instance, which we do not want for these simple
examples.

Yet, as a result, the dependencies are less accurate, there is code
duplication, etc.  This is especially perceptible when trying to
extract more examples from the documentation, as will be done in
forthcoming changes.

In order to make the tuning of CPPFLAGS easier, discard the predefined
-I from Automake.

	* examples/calc++/Makefile.am: Rename as...
	* examples/calc++/local.mk: this.
	Adjust the paths which are now rooted in top_srcdir/top_builddir.
	Handle BISON_CXX_WORKS here, instead of the too crude previous
	approach that completely discarded the whole directory.
	($(BISON)): Remove now useless bouncing recipe.
	(calc___CPPFLAGS): New.
	Stay away from -Ilib.
	* Makefile.am, configure.ac, examples/local.mk,
	* examples/calc++/test: Adjust.

	* configure.ac: Pass nostdinc to Automake.
	* src/local.mk, lib/local.mk (AM_CPPFLAGS): Move to...
	* Makefile.am: here.

	* src/local.mk, examples/calc++/Makefile.am (BISON, BISON_IN): Factor
	to...
	* Makefile.am: here.
	* tests/local.mk: Use it.

examples/calc++/local.mk

@@ -0,0 +1,94 @@
+## Process this file with automake to produce Makefile.in -*-Makefile-*-
+
+## Copyright (C) 2005-2006, 2008-2012 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/>.
+
+## ------------ ##
+## Extracting.  ##
+## ------------ ##
+
+doc = $(top_srcdir)/doc/bison.texinfo
+extexi = $(top_srcdir)/examples/extexi
+# Extract in src.
+$(top_srcdir)/examples/calc++/calc.stamp: $(doc) $(extexi)
+	$(AM_V_GEN)rm -f $@ $@.tmp
+	$(AM_V_at)touch $@.tmp
+	$(AM_V_at)cd $(top_srcdir)/examples/calc++ && \
+	   $(AWK) -f ../extexi -v VERSION="$(VERSION)" \
+	     ../../doc/bison.texinfo -- calc++-parser.yy \
+	     calc++-scanner.ll calc++.cc calc++-driver.hh calc++-driver.cc
+	$(AM_V_at)mv $@.tmp $@
+
+$(calc_extracted): $(top_srcdir)/examples/calc++/calc.stamp
+
+## ------------------- ##
+## Parser generation.  ##
+## ------------------- ##
+
+BUILT_SOURCES += $(calc_extracted) $(calc_sources_generated)
+CLEANFILES += $(top_srcdir)/examples/calc++/*.output *.tmp
+MAINTAINERCLEANFILES += $(top_srcdir)/examples/calc++/*.stamp $(calc___SOURCES)
+
+# Compile the parser and save cycles.
+# This code comes from "Handling Tools that Produce Many Outputs",
+# from the Automake documentation.
+EXTRA_DIST +=					\
+  examples/calc++/calc++-parser.stamp		\
+  examples/calc++/calc++-parser.yy		\
+  examples/calc++/calc.stamp
+# Don't depend on $(BISON) otherwise we would rebuild these files
+# in srcdir, including during distcheck, which is forbidden.
+$(top_srcdir)/examples/calc++/calc++-parser.stamp: $(top_srcdir)/examples/calc++/calc++-parser.yy $(BISON_IN)
+	$(AM_V_GEN)rm -f calc++-parser.tmp
+	$(AM_V_at)touch calc++-parser.tmp
+	$(AM_V_at)$(BISON) -d -ra -o $(top_srcdir)/examples/calc++/calc++-parser.cc \
+	  $(top_srcdir)/examples/calc++/calc++-parser.yy
+	$(AM_V_at)mv -f calc++-parser.tmp $@
+
+$(calc_sources_generated): $(top_srcdir)/examples/calc++/calc++-parser.stamp
+	$(AM_V_GEN)if test -f $@; then :; else \
+	  rm -f $(top_srcdir)/examples/calc++/calc++-parser.stamp && \
+	  $(MAKE) $(AM_MAKEFLAGS) $(top_srcdir)/examples/calc++/calc++-parser.stamp; \
+	fi
+
+
+## --------------------------- ##
+## Building & testing calc++.  ##
+## --------------------------- ##
+
+calc_sources_extracted =			\
+  examples/calc++/calc++-scanner.ll		\
+  examples/calc++/calc++.cc			\
+  examples/calc++/calc++-driver.hh		\
+  examples/calc++/calc++-driver.cc
+calc_extracted =				\
+  $(calc_sources_extracted)			\
+  examples/calc++/calc++-parser.yy
+calc_sources_generated =			\
+  examples/calc++/stack.hh			\
+  examples/calc++/position.hh			\
+  examples/calc++/location.hh			\
+  examples/calc++/calc++-parser.hh		\
+  examples/calc++/calc++-parser.cc
+
+if BISON_CXX_WORKS
+check_PROGRAMS = examples/calc++/calc++
+examples_calc___calc___SOURCES =		\
+  $(calc_sources_extracted) 			\
+  $(calc_sources_generated)
+examples_calc___calc___CPPFLAGS = -I$(top_srcdir)/examples/calc++
+TESTS = examples/calc++/test
+endif
+EXTRA_DIST += examples/calc++/test