Add the minimal Tajik locale part 2

Add lang/tg.txt to get GetAvailableLocale not return Tajik.

R=rouslan@chromium.org
TBR=rouslan@chromium.org
BUG=354658
TEST=See the bug.

Review URL: https://codereview.chromium.org/211623002

git-svn-id: https://src.chromium.org/chrome/trunk/deps/third_party/icu46@259309 4ff67af0-8c30-449e-8e8b-ad334ec8d88c