Must add locations to the profile when generating a profile.proto.
This fixes #18229

Change-Id: I49cd63a30759d3fe8960d7b7c8bd5a554907f8d1
Reviewed-on: https://go-review.googlesource.com/34028Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>