make.bat: do not exit builder on successful completion of make.bat (fixes build)
make.bat: do not exit builder on successful completion of make.bat (fixes build)

LGTM=dvyukov
R=golang-codereviews, dvyukov
CC=golang-codereviews
https://codereview.appspot.com/118020043

tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go