Treat it as okay if no packages are found when loading all the packages in a
workspace. Users may open workspaces that don't have any Go files, either because
they are workspaces for other languages, or because no Go files have been created
yet.
Fixesgolang/go#35455
Change-Id: I60912472ec8930649996edc150d1d19cd74a0a2e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/206140
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>