The copyright message already appears at the top of macho.go. Drop the
duplicate further down in the file.

Change-Id: Ib0a69f568c4ef656bab14176223936cd2fe078d1
Reviewed-on: https://go-review.googlesource.com/115235
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>