On an Android build, API 22, at least, I got a:
> warning: "UNIX_PATH_MAX" redefined

We were currently defining it as:
> #define UNIX_PATH_MAX sizeof (((struct sockaddr_un *) 0)->sun_path)
Whereas Android's headers define this variable of sockaddr_un as:
> char sun_path[UNIX_PATH_MAX];
So by definition, we will still get the right result in the end by just
using the original value of UNIX_PATH_MAX.