Merge branch 'epoll'

src/header/fcntl/linux.rs

src/header/fcntl/mod.rs

src/header/fcntl/redox.rs

src/header/mod.rs

src/header/poll/mod.rs

src/header/sys_epoll/cbindgen.toml

src/header/sys_epoll/linux.rs

src/header/sys_epoll/mod.rs

src/header/sys_epoll/redox.rs

src/header/sys_select/mod.rs

src/platform/linux/epoll.rs

src/platform/linux/mod.rs

src/platform/mod.rs

src/platform/pal/epoll.rs

src/platform/pal/mod.rs

src/platform/redox/mod.rs