go/build: include files with parse errors in GoFiles and other lists

go/build.ImportDir returns a *build.Package with various lists of
files. If a file is invalid for some reason, for example, because it
has a different package name than other files, it's added to
InvalidGoFiles in addition to GoFiles, TestGoFiles, or other lists.

Previously, files with parse errors or build constraint errors were
not included in these lists, which causes problems for tools that use
'go list' since InvalidGoFiles is not printed. With this change, files
with any kind of error are added to one of the GoFiles lists.

Fixes #39986

Change-Id: Iee007b5092293eb4420c8a39ce731805fe32135f
Reviewed-on: https://go-review.googlesource.com/c/go/+/241577


Trust: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>