internal/txtar: bring back to main repo, for tests in std

This used to be cmd/go/internal/txtar,
and then it was moved to golang.org/x/tools/txtar
and revendored from there into cmd/vendor/golang.org/x/tools/txtar.

We have a use for txtar in a new test in the standard library,
which cannot access cmd/vendor. But we also don't really want
to vendor it into the standard library as is, because that would
be the first vendoring of x/tools in std, and it would be better
to keep std separate from x/tools, even for testing.

Instead, since a little copying is better than a little dependency,
just make a copy in internal/txtar. The package does not change.

Having done that, replace the uses in cmd/go so that there's
only one copy in the main repo.

Change-Id: I70b5cc05da3f6ebcc0fd9052ebcb3d369fb57956
Reviewed-on: https://go-review.googlesource.com/c/go/+/384254
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

0 files changed, 0 insertions, 0 deletions