syscall: replace lstat, lchown, stat to please Android O

syscall: replace lstat, lchown, stat to please Android O

Implement Lstat with fstatat and Lchown with Fchownat on
linux/amd64, linux/arm and linux/386. Furthermore, implement Stat
with fstatat on linux/arm and linux/386. Linux/arm64 already had
similar replacements.

The fstatat and fchownat system calls were added in kernel 2.6.16,
which is before the Go minimum, 2.6.23.

The three syscalls then match the android bionic implementation
and avoids the Android O seccomp filter.

Fixes #27797

Change-Id: I07fd5506955d454a1a660fef5af0e1ac1ecb0959
Reviewed-on: https://go-review.googlesource.com/136795
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>