httrack: upstream patch to fix build pre-10.7

Fixes #31789.
dart 1.6.0

update to dart sdk 1.6

Closes #31928.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
Remove to_str from Option

We no longer need implicit conversion of options to strings.
gettext: Add keg_only :provided_by_osx
gettext: update 0.19.2 bottle.