libdot 1.3: Fix concat.sh append_string

* Fix append_string to work with multi-line strings.

BUG=None
TEST=None

Change-Id: I79319453a54e1719bc47a96c79b2aa58b485d3fd
Reviewed-on: https://gerrit.chromium.org/gerrit/56610
Reviewed-by: Marius Schilder <mschilder@google.com>
Commit-Queue: Robert Ginda <rginda@chromium.org>
Reviewed-by: Robert Ginda <rginda@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>
4 files changed
tree: 4d1d0b4fe314a22231e43a8e42200123b4f5379f
  1. crosh_builtin/
  2. hterm/
  3. libdot/
  4. nassh/