[dev.cc] all: merge dev.power64 (f57928630b36) into dev.cc

This will be the last dev.power64 merge; we'll finish on dev.cc.

TBR=austin
CC=golang-codereviews
https://golang.org/cl/175420043

diff --cc src/cmd/5g/reg.c
Simple merge

diff --cc src/cmd/8g/reg.c
Simple merge

diff --cc src/liblink/list9.c
Simple merge