[dev.link] all: merge branch 'master' into dev.link

Clean merge.

Change-Id: If9bfb0f27f41563fd5d386de9c1081542c3ce498

diff --cc src/cmd/compile/internal/gc/main.go
Simple merge

diff --cc src/cmd/internal/obj/sizeof_test.go
Simple merge

diff --cc src/cmd/link/internal/ld/data.go
Simple merge