Bug fixes for fcntl and o_cloexec

src/context/context.rs

src/context/file.rs

src/scheme/debug.rs

src/scheme/env.rs

src/scheme/event.rs

src/scheme/initfs.rs

src/scheme/irq.rs

src/scheme/live.rs

src/scheme/memory.rs

src/scheme/null.rs

src/scheme/pipe.rs

src/scheme/sys/iostat.rs

src/scheme/sys/mod.rs

src/scheme/sys/scheme.rs

src/scheme/sys/scheme_num.rs

src/scheme/time.rs

src/scheme/zero.rs

src/syscall/fs.rs

src/syscall/process.rs