go list functionality changed in 1.11 and compatibility logic was added
to support 1.10 and before. Now that Go 1.12 has been released, support
for those version has ended and we can remove the legacy code.
Change-Id: Ifdd5c566dbbfe4fade5be27ad9ae20052d604c15
Reviewed-on: https://go-review.googlesource.com/c/tools/+/166537
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>