若不更新链接，运行时可能会发生错误：
./a.out: /usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.14' not found (required by ./a.out)
strings /usr/lib64/libstdc++.so.6 | grep GLIBC
strings /usr/local/lib64/libstdc++.so.6.0.19 | grep GLIBC
root在/usr/lib64目录下创建软链接
ln -sf /usr/local/lib64/libstdc++.so.6.0.19 libstdc++.so.6