Our Red Bear patches had reverted the userspace fd allocation refactor
(commit 372b200f) in exec.rs. This caused FD tracking mismatches
between the userspace FILETABLE and the kernel fd table, resulting in
EEXIST errors and fork failures.
Restored the upstream version which correctly uses redox_rt::sys::*
functions (openat, dup, sys_call_ro) that go through the FILETABLE,
and openat_into_upper for pre-init FD allocation. Also includes the
filetable_binary_fd setup and same_process flag in ExtraInfo.
Red Bear OS
75f6cf902d