交叉编译详解:https://www.crifan.com/files/doc/docbook/cross_compile/release/html/cross_compile.html#purpose
crosstool-ng详解：https://www.crifan.com/files/doc/docbook/crosstool_ng/release/html/crosstool_ng.html
crosstool-ng的基本使用流程：
https://gaomf.cn/2016/06/15/crosstool-ng%E7%9A%84%E5%9F%BA%E6%9C%AC%E4%BD%BF%E7%94%A8%E6%B5%81%E7%A8%8B/
https://jingyan.baidu.com/article/1974b2898601baf4b1f77403.html
https://www.cnblogs.com/andyfly/p/10507600.html