Use SOCK_CLOEXEC and accept4() on more platforms.
Use SOCK_CLOEXEC and accept4() on more platforms.

graydon/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust