This CL is a pure refactoring to replace go/build usage with golang.org/x/tools/go/packages. This is a preparation for Go modules. Updates golang/go#27234 Change-Id: I3e6a30b962da1a64bc43a89a7f02c03d559f86d3 Reviewed-on: https://go-review.googlesource.com/c/mobile/+/189597 Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>