internal/syscall/unix: fix syscalls for alpha, ia64, s390

Also change the configure script to set GOARCH correctly for ia64, and
add ia64 as a processor to match.sh and gotest.

Change-Id: I3c0a6255149a9605ab631d9d2623f7c7306c87c1
Reviewed-on: https://go-review.googlesource.com/25549
Reviewed-by: Ian Lance Taylor <iant@golang.org>
7 files changed