io.rs uses redox_syscall::dup, ::CallFlags, ::ProcSchemeVerb but was
missing the 'use syscall as redox_syscall' alias (was removed earlier
because cargo check passed locally without it, but actual build needs it).
Also fixed: the non-redox arm of acquire_iopl was using crate::Result
which is a 1-generic type alias; std::result::Result with 2 generics
is what's needed here.
Removed leftover cfg attribute and duplicate use crate::Result.
vasilito
c43d3eddd9