This change depends on CL 57170052. LGTM=rsc R=rsc, bradfitz CC=golang-codereviews https://golang.org/cl/60840049
Set $status as null to prevent rc from exiting on the last --no-banner argument checking when used with rc -e. It allows all.rc to not exit before executing run.rc R=golang-dev, lucio.dere, rsc CC=golang-dev https://golang.org/cl/9611045
Also, I synced the rc files with changes that have been made to make.bash, etc. R=seed, rminnich, r CC=golang-dev https://golang.org/cl/7389049
R=rsc, iant, iant, seed CC=golang-dev https://golang.org/cl/5608059
