x/sys/unix: syscall_linux_test.go FileDedupeRange test fails on ZFS

[lanodan]

• Linux 6.6.21-gentoo
• OpenZFS 2.2.2
• Go 1.22.4
• x/sys 0.22.0

Test log:

ok      golang.org/x/sys/cpu    0.002s
ok      golang.org/x/sys/execabs        0.003s
--- FAIL: TestIoctlFileDedupeRange (0.00s)
    syscall_linux_test.go:1093: Unexpected error in FileDedupeRange: ENOTSUP
    syscall_linux_test.go:1098: Unexpected amount of bytes deduped 0 != 4096
    syscall_linux_test.go:1108: Unexpected error in FileDedupeRange: ENOTSUP
FAIL
FAIL    golang.org/x/sys/unix   0.594s
FAIL

[lanodan]

Also seems to be reproducible inside a tmpfs.

[gopherbot]

Change https://go.dev/cl/597555 mentions this issue: unix: skip TestIoctlFileDedupeRange on EOPNOTSUPP error

[cagedmantis]

cc @golang/runtime

[lanodan]

Change https://go.dev/cl/597555 mentions this issue: `unix: skip TestIoctlFileDedupeRange on EOPNOTSUPP error`

With this change tests pass successfully. Thanks!