examples: adding the examples folder to the build

After including the doc/ and the tests/ folder under the hood of the
autotools now adding the examples/ foolder too.
The user is now able to add the build of the example binarys if
configure is called with '--enable-examples' as option. The example
binarys will not be build by default!

Currently only 'coap-client', 'coap-server' and 'rd' is build.

Makefile.am

@@ -14,7 +14,7 @@ ACLOCAL_AMFLAGS = ${ACLOCAL_FLAGS} -I m4
 
 AM_CFLAGS = -I @top_builddir@/include/coap/ $(WARNING_CFLAGS) -std=c99
 
-SUBDIRS = . $(DOC_DIR) tests
+SUBDIRS = . $(DOC_DIR) tests examples
 
 ## Define a libtool archive target "libcoap-@LIBCOAP_API_VERSION@.la", with
 ## @LIBCOAP_API_VERSION@ substituted into the generated Makefile at configure

configure.ac

@@ -222,6 +222,22 @@ if test "x$build_tests" = "xyes"; then
 fi
 AM_CONDITIONAL(HAVE_CUNIT, [test "x$CUNIT_LIBS" != "x"])
 
+# configure options
+# __examples__
+AC_ARG_ENABLE([examples],
+              [AC_HELP_STRING([--enable-examples],
+              [Enable building the tests (default=yes)])],
+              [build_examples="$enableval"],
+              [build_examples="yes"])
+
+if test "x$build_examples" = "xyes"; then
+	BUILD_EXAMPLES="YES"
+fi
+AM_CONDITIONAL(BUILD_EXAMPLES, [test "x$build_examples" != "x"])
+
+# end configure options
+#######################
+
 # Check for ctags
 AC_ARG_VAR([CTAGS_PROG],[the 'ctag' program to use for make target 'update-map-file'])
 AC_PATH_PROG([CTAGS_PROG],[ctags],[])
@@ -305,6 +321,7 @@ esac
 AC_CONFIG_FILES([
 Makefile
 doc/Makefile
+examples/Makefile
 tests/Makefile
 libcoap-$LIBCOAP_API_VERSION.pc:libcoap-$LIBCOAP_API_VERSION.pc.in
 ])
@@ -335,3 +352,6 @@ if test "x$build_tests" = "xyes"; then
 else
 	AC_MSG_RESULT([      build unit test binary  : "no"])
 fi
+if test "x$build_examples" = "xyes"; then
+	AC_MSG_RESULT([      build examples          : "yes"])
+fi

examples/Makefile.am

@@ -0,0 +1,28 @@
+# doc/Makefile.am
+#
+# Copyright (C)      2015 Carsten Schoenert <c.schoenert@t-online.de>
+#
+# This file is part of the CoAP C library libcoap. Please see README and
+# COPYING for terms of use.
+
+# just do nothing if 'BUILD_EXAMPLES' isn't defined
+if BUILD_EXAMPLES
+
+# picking up the default warning CFLAGS into AM_CFLAGS
+AM_CFLAGS = -I@top_builddir@/include/coap/ $(WARNING_CFLAGS) -std=c99
+
+# etsi_iot_01 and tiny are missing
+bin_PROGRAMS = coap-client coap-server rd
+
+coap_client_SOURCES = client.c coap_list.c
+coap_client_LDADD = @top_builddir@/.libs/libcoap-$(LIBCOAP_API_VERSION).la
+
+coap_server_SOURCES = server.c
+coap_server_LDADD = @top_builddir@/.libs/libcoap-$(LIBCOAP_API_VERSION).la
+
+rd_SOURCES = rd.c
+rd_LDADD = @top_builddir@/.libs/libcoap-$(LIBCOAP_API_VERSION).la
+
+install-exec-am: all-local
+
+endif # BUILD_EXAMPLES