cmd: update x/tools version to enforce only one %w

As mentioned in https://golang.org/issue/34062#issuecomment-529692313
src/cmd refers to older version of golang.org/x/tools.
Hence, not checking if multiple errors are used in the same fmt.Errorf.
Updating golang.org/x/tools version to latest in src/cmd.

Fixes #34062

Change-Id: I358dec2c3d3af2b19add766b8488b919109b81d6
Reviewed-on: https://go-review.googlesource.com/c/go/+/196843


Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>