The command "go tool pprof help" does not work:

    $ go tool pprof help
    open help: no such file or directory

The right command is "go tool pprof -h".

Change-Id: Icef5d4ab76774905854e46665ac1166d26d35f46
Reviewed-on: https://go-review.googlesource.com/10970Reviewed-by: Ian Lance Taylor <iant@golang.org>