This applies the following CLs from the syscall package:
http://golang.org/cl/9962
http://golang.org/cl/9966
http://golang.org/cl/9924

It also adds arm64/ppc64 support to mkall.sh and mksysnum_linux.pl.

Change-Id: I84fbfde2a2876dbf6d16c6159e847195c274b396
Reviewed-on: https://go-review.googlesource.com/10037Reviewed-by: Rob Pike <r@golang.org>