Because ARM ABI requires 64-bit argument to be passed in even
register pairs, to avoid wasting one register between fd and
advise in the usual fadvise64 syscall signature, linux/arm
has its own variation that reorders the argument so that the
arguments fit in six registers.

While we're at it, also fix build for linux/386.

Fixes golang/go#10294.

Change-Id: I322e2226619c5aa9c096a1d5cb7ae1e94fd4a5a1
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/8282Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>