message: Added some constants in linux for file modes
diff: @@ -18,6 +18,12 @@ pub const O_CREAT: c_int = 0x0040;
  pub const O_TRUNC: c_int = 0x0200;
  #[cfg(target_os = "linux")]
  pub const O_ACCMODE: c_int = O_RDONLY | O_WRONLY | O_RDWR;
  +#[cfg(target_os = "linux")]
  +pub const O_APPEND: c_int = 0o2000;
  +#[cfg(target_os = "linux")]
  +pub const O_CLOEXEC: c_int = 0o2_000_000;
  +#[cfg(target_os = "linux")]
  +pub const O_EXCL: c_int = 0o200;
  #[cfg(target_os = "redox")]
  pub const O_RDONLY: c_int = 0x0001_0000;
  