libXt: Add package from upstream

Upgraded x11-libs/libXt to version 1.2.1 on amd64 to support X features
in Vim.

BUG=none
TEST=USE="X" emerge app-editors/vim
TEST=Copy/paste via X clipboard and vim register

Change-Id: I76f0de6db47bf5dcd4d93b413825794abf73d1ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3277047
Commit-Queue: Abe Levkoy <alevkoy@chromium.org>
Commit-Queue: Raul E Rangel <rrangel@chromium.org>
Tested-by: Abe Levkoy <alevkoy@chromium.org>
Auto-Submit: Abe Levkoy <alevkoy@chromium.org>
Reviewed-by: Raul E Rangel <rrangel@chromium.org>
4 files changed