Squashed commit of the following:

    psock_close() and net_close() are internal OS functions and should not set the errno variable.

    psock_ioctl() and netdev_ioctl() are internal OS functions and should not set the errno variable.

    net_dupsd() and net_dupsd2() are internal OS functions and should not set the errno variable.

    net/ and fs/: net_vfcntl(), file_fcntl(), file_dup(), and file_dup2() are all internal OS interfaces and should not modify the errno value.