On AIX, Stat_t's fields dealing with time are of type StTimespec while
all other GOOS are using Timespec.
StTimespec and Timespec are the same on ppc but not in ppc64. Therefore,
values returned by ppc64 syscalls need to be adjusted in order to
allow the use of Timespec instead of StTimespec.
Fixesgolang/go#32073
Change-Id: I0c212bf1741a27c49e995bf928d4941b6d583e54
Reviewed-on: https://go-review.googlesource.com/c/sys/+/177838
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>