This change has no code modifications. Just move the handling for
overlays and debugging into separate files to make them easier to find.
Also, add some missing copyrights.
Change-Id: I7256f704c017457fa3418818d03f89f061af6fc9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/211757
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Rebecca Stambler