cpu: don't redeclare doinit on ppc64le
cpu: don't redeclare doinit on ppc64le

Follow-up fix for CL 206859. Also order the +build line alphabetically.

Change-Id: I568c8b3ee03161d4341c151e4ec7150cade51077
Reviewed-on: https://go-review.googlesource.com/c/sys/+/206864
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/sys,golang/sys,golang/sys,multiplay/golang-sys,multiplay/golang-sys,multiplay/golang-sys,multiplay/golang-sys