x/sys/unix: TestStatx fails on linux-arm64-packet builder

[hyangah]

https://build.golang.org/log/352dedb67faf09e91e7a33d1ec1596eefc5ceb86

--- FAIL: TestStatx (0.00s)
syscall_linux_test.go:291: Statx: operation not permitted
FAIL
FAIL cmd/vendor/golang.org/x/sys/unix 0.400s

[gopherbot]

Change https://golang.org/cl/114093 mentions this issue: unix: skip TestStatx if the operation is not permitted

[gopherbot]

Change https://golang.org/cl/114094 mentions this issue: cmd/vendor/.../unix: pick up upstream fixes for broken tests