Refactor the overlay code to create package structs for
new packages that don't already exist. This requires
calling out to the go command to determine module
roots to figure out which module a package belongs to.
The extra go list call is done in sequence in this CL
but can easily be done in parallel with other go list
calls in the future.
Change-Id: Ia0f7812fba250d154033038cb1e2afa7dedf0e16
Reviewed-on: https://go-review.googlesource.com/c/tools/+/179600
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
75312fb067