libredox O_CLOEXEC now references syscall::flag::O_CLOEXEC instead
of duplicating the literal 0x0100_0000. Per Single Source of Truth
and the Local Fork Supremacy Policy: a primitive constant should be
defined once in the most-primitive crate that has it (syscall) and
re-exported by higher-level crates (libredox).
vasilito
7b1236b320