When module is enabled, the go tool embeds build information
related to the module in the binary including the dependencies
and the replace information (See
src/cmd/go/internal/modload.PackageBuildInfo).

The newly introduced ReadBuildInfo reads the information and
makes it accessible programmatically.

Update #26404

Change-Id: Ide37022d609b4a8fb6b5ce02afabb73f04fbb532
Reviewed-on: https://go-review.googlesource.com/c/144220
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>