examples: factor the test suite.

* examples/mfcalc/test, examples/calc++/test: Extract the
	common bits into...
	* examples/test: here.
	(cwd): New.
	Use it to avoid a race on the temporary directory.
	Reported by Jim Meyering.
	* examples/mfcalc/test, examples/calc++/test: Rename into...
	* examples/mfcalc/mfcalc.test, examples/calc++/calc++.test: these.
	* examples/calc++/local.mk, examples/mfcalc/local.mk,
	* examples/local.mk: Adjust.

examples/test

@@ -0,0 +1,79 @@
+#! /bin/sh
+set -x
+# Copyright (C) 2005-2012 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/>.
+
+me=`basename $1 .test`
+
+# Number of the current test.
+number=1
+
+# Exit status of this script.
+exit=true
+
+# top_buiddir.
+cwd=`pwd`
+
+# The exercised program.
+prog=$cwd/examples/$me/$me
+
+# cleanup
+# -------
+cleanup ()
+{
+  local status=$?
+  if test -z "$DEBUG"; then
+     cd $cwd
+     rm -rf $$.dir
+  fi
+  exit $status
+}
+trap cleanup 0 1 2 13 15
+mkdir $$.dir
+cd $$.dir
+
+# run EXPECTED-EXIT-STATUS EXPECTED-OUTPUT [PARSER-OPTIONS]
+# ---------------------------------------------------------
+run ()
+{
+  # Expected exit status.
+  local sta_exp=$1
+  shift
+  # Expected output.
+  local out_exp=$1
+  shift
+  $prog "$@" - <input >out_eff
+  # Effective exit status.
+  local sta_eff=$?
+  # Effective output.
+  local out_eff=`cat out_eff`
+  if test $sta_eff -eq $sta_exp; then
+    if test "$out_eff" = "$out_exp"; then
+      echo "$me: PASS: $number"
+    else
+      echo "$me: FAIL: $number (expected output: $out_exp, effective: $out_eff)"
+      exit=false
+    fi
+  else
+    echo "$me: FAIL: $number (expected status: $sta_exp, effective: $sta_eff)"
+    exit=false
+  fi
+  number=`expr $number + 1`
+}
+
+# We have cd'd one level deeper.
+. "../$1"
+
+$exit