CentoOS 7 下：
python 3.6
libxml 编译时，提示python编译报错：
/usr/bin/ld: /usr/local/python3/lib/python3.6/config-3.6m-x86_64-linux-gnu/libpython3.6m.a(abstract.o): relocation R_X86_64_32S against `_Py_NotImplementedStruct’ can not be used when making a shared object; recompile with -fPIC
/usr/local/python3/lib/python3.6/config-3.6m-x86_64-linux-gnu/libpython3.6m.a: could not read symbols: Bad value
collect2: error: ld returned 1 exit status
说明python需要重新编译，添加-fPIC选项。
python编译配置命令为：
./configure --prefix=/usr/local/python3 --enable-shared CFLAGS=-fPIC --enable-optimizationsmakemake install
重新编译安装python后， 再来编译 libxml 就不会报错了。