pycocotools/_mask.c: No such file or directory 问题

在官方的github的issue中大家讨论了这个问题：

https://github.com/cocodataset/cocoapi/issues/172

最全面的方案如下

1. whether you have installed cython in the correct version. Namely you should install cython for python2/3 if you use python2/3
2. whether you have downloaded the whole .zip file from this github project. Namely, you should download all the things here even though you only need PythonAPI
3. whether you open Terminal and run "make" under the correct folder. The correct folder is the one that "Makefile" is located in
4. whether you have already installed gcc in the correct version
5. whether you have already installed python-dev in the correct version. Namely you should install python3-dev (you may try "sudo apt-get install python3-dev"), if you use python3.

一般就是

pip install cython

或者使用 python3来安装。但是我在使用的过程中尝试了所有的方法都不行，后来我把cocoapi的权限降到了可读可写，就能编译成功了。

sudo chmod -R 777 cocoapi