- Rename `syscall_linux.go` to `syscall.go` with build constraints for non-BSD and non-Windows platforms.
- Merge `syscall_darwin.go` into `syscall_bsd.go` and adjust build constraints for BSD platforms (Darwin, FreeBSD, OpenBSD).
- Remove redundant `syscall_freebsd.go`.
- Add build constraints to `syscall_windows.go` for Windows platform.

- Rename `device_freebsd.go` to `device_bsd.go` and `hardware_freebsd.go` to `hardware_bsd.go` to reflect broader BSD support (FreeBSD, NetBSD, OpenBSD, Dragonfly).
- Update build tags in `device_bsd.go` and `hardware_bsd.go` to include FreeBSD, NetBSD, OpenBSD, and Dragonfly.
- Rename `device_linux.go` to `device_unix.go` and `hardware_linux.go` to `hardware_unix.go` to generalize Unix support excluding Darwin-based systems and BSDs.
- Add specific build tags to `device_darwin.go`, `device_unix.go`, `hardware_darwin.go`, and `hardware_unix.go` to correctly target their respective operating systems.
- Ensure Windows-specific files (`device_windows.go` and `hardware_windows.go`) are correctly tagged for building on Windows.

…ore-generic