This change adds a Logf field to the packages.Config.
Change-Id: I144a9a1e1181585bbe621898c4a3e6a007a38322
Reviewed-on: https://go-review.googlesource.com/c/tools/+/185993
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>