examples: d: duplicate the example as "simple" and "calc"

* examples/d/Makefile, examples/d/calc.d, examples/d/calc.test,
examples/d/calc/local.mk: Move into...
* examples/d/calc, examples/d/simple: these new directories.

examples/d/simple/local.mk

@@ -0,0 +1,36 @@
+## Copyright (C) 2018-2020 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/>.
+
+simpleddir = $(docdir)/%D%
+
+## ------ ##
+## Calc.  ##
+## ------ ##
+
+if ENABLE_D
+  check_SCRIPTS += %D%/calc
+  TESTS += %D%/calc.test
+endif
+EXTRA_DIST += %D%/calc.test
+
+%D%/calc.d: %D%/calc.y $(dependencies)
+	$(AM_V_GEN)$(MKDIR_P) %D%
+	$(AM_V_at)$(BISON) -o $@ $(srcdir)/%D%/calc.y
+
+%D%/calc: %D%/calc.d
+	$(AM_V_GEN) $(DC) $(DCFLAGS) -of$@ %D%/calc.d
+
+dist_simpled_DATA = %D%/calc.y %D%/Makefile
+CLEANFILES += %D%/calc %D%/calc.[do]