how to build tbox xml into the demo

I saw https://blog.csdn.net/gitblog_00889/article/details/151057353 says the tbox tool has xml reader/writer functions. so
I download the code from https://github.com/tboox/tbox/releases/tag/v1.7.7 , then unzip it.
build the xml functions into the demo as following steps:

1. cd tbox-1.7.7 and ./configure
2. modified tbox.config.h under build/linux/x86_64/release, add one line

#define TB_CONFIG_MODULE_HAVE_XML 1

modified demo.c under src/demo, add one line

#define TB_CONFIG_MODULE_HAVE_XML 1

3. make
   it reports

/usr/bin/ld: build/.objs/demo/linux/x86_64/release/src/demo/demo.c.o:(.rodata+0x98): undefined reference to `tb_demo_xml_reader_main'
/usr/bin/ld: build/.objs/demo/linux/x86_64/release/src/demo/demo.c.o:(.rodata+0xa8): undefined reference to `tb_demo_xml_writer_main'
/usr/bin/ld: build/.objs/demo/linux/x86_64/release/src/demo/demo.c.o:(.rodata+0xb8): undefined reference to `tb_demo_xml_document_main'
collect2: error: ld returned 1 exit status
make: *** [makefile:1417: build/linux/x86_64/release/demo] Error 1

4. then I add following lines into makefile

build/.objs/demo/linux/x86_64/release/src/demo/xml/document.c.o: src/demo/xml/document.c
	@echo compiling.release src/demo/xml/document.c
	@mkdir -p build/.objs/demo/linux/x86_64/release/src/demo/xml
	$(VV)$(cc) -c $(demo_cflags) -o build/.objs/demo/linux/x86_64/release/src/demo/xml/document.c.o src/demo/xml/document.c

build/.objs/demo/linux/x86_64/release/src/demo/xml/reader.c.o: src/demo/xml/reader.c
	@echo compiling.release src/demo/xml/reader.c
	@mkdir -p build/.objs/demo/linux/x86_64/release/src/demo/xml
	$(VV)$(cc) -c $(demo_cflags) -o build/.objs/demo/linux/x86_64/release/src/demo/xml/reader.c.o src/demo/xml/reader.c

build/.objs/demo/linux/x86_64/release/src/demo/xml/writer.c.o: src/demo/xml/writer.c
	@echo compiling.release src/demo/xml/writer.c
	@mkdir -p build/.objs/demo/linux/x86_64/release/src/demo/xml
	$(VV)$(cc) -c $(demo_cflags) -o build/.objs/demo/linux/x86_64/release/src/demo/xml/writer.c.o src/demo/xml/writer.c
	

build/.objs/tbox/linux/x86_64/release/src/tbox/xml/node.c.o: src/tbox/xml/node.c
	@echo compiling.release src/tbox/xml/node.c
	@mkdir -p build/.objs/tbox/linux/x86_64/release/src/tbox/xml
	$(VV)$(cc) -c $(tbox_cflags) -o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/node.c.o src/tbox/xml/node.c
 
build/.objs/tbox/linux/x86_64/release/src/tbox/xml/reader.c.o: src/tbox/xml/reader.c
	@echo compiling.release src/tbox/xml/reader.c
	@mkdir -p build/.objs/tbox/linux/x86_64/release/src/tbox/xml
	$(VV)$(cc) -c $(tbox_cflags) -o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/reader.c.o src/tbox/xml/reader.c

build/.objs/tbox/linux/x86_64/release/src/tbox/xml/writer.c.o: src/tbox/xml/writer.c
	@echo compiling.release src/tbox/xml/writer.c
	@mkdir -p build/.objs/tbox/linux/x86_64/release/src/tbox/xml
	$(VV)$(cc) -c $(tbox_cflags) -o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/writer.c.o src/tbox/xml/writer.c

I also add strings at the end of following two positions,

tbox: build/linux/x86_64/release/libtbox.a
build/linux/x86_64/release/libtbox.a: 
...
build/.objs/tbox/linux/x86_64/release/src/tbox/xml/node.c.o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/reader.c.o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/writer.c.o
...
build/.objs/tbox/linux/x86_64/release/src/tbox/xml/node.c.o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/reader.c.o build/.objs/tbox/linux/x86_64/release/src/tbox/xml/writer.c.o


demo: build/linux/x86_64/release/demo
build/linux/x86_64/release/demo: 
...
build/.objs/demo/linux/x86_64/release/src/demo/xml/document.c.o build/.objs/demo/linux/x86_64/release/src/demo/xml/reader.c.o build/.objs/demo/linux/x86_64/release/src/demo/xml/writer.c.o
...
build/.objs/demo/linux/x86_64/release/src/demo/xml/document.c.o build/.objs/demo/linux/x86_64/release/src/demo/xml/reader.c.o build/.objs/demo/linux/x86_64/release/src/demo/xml/writer.c.o

5. run make again
   It build the demo and libtbox.a under /build/linux/x86_64/release .

6. run

build/linux/x86_64/release/demo xml_writer a.xml

it build the file a.xml.

build/linux/x86_64/release/demo xml_reader a.xml
<?xml version = "1.0" encoding = "utf-8" ?>
<!--comments ...-->
<labels name = "hello world">


        <label_1 label = "1" id = "1">

                characters

        </label_1>


        <label_2 id = "2" bool = "true">

                characters

        </label_2>


        <label_3 label = "3" id = "3">

                characters

                <label_4 id = "-4" bool = "false"/>


                <label_5/>


        </label_3>


        <![CDATA[datas]]>
</labels>

it print the content of the file a.xml we just wrote. adding the blank lines as above,

build/linux/x86_64/release/demo xml_document a.xml b.xml

it wrote the content of the file a.xml to b.xml, also adding the blank lines as above.