erroneous assert encoded >= 0xf001

This one: https://github.com/bytecodealliance/rustix/blob/cd9520157e08e4e70b2fc9c2e9aacb18c8d23439/src/backend/linux_raw/io/errno.rs#L91 Is causing issues here: https://github.com/Smithay/smithay/issues/1725 . I think the issue is that the assert fails when errno is `0`, because wrapping_neg puts it back to `0`. This is also what is shown in my corefile of the crash <img width="159" height="57" alt="Image" src="https://github.com/user-attachments/assets/fc5f5c1a-1bb1-4e3e-95dc-7802e51aed76" />