ab097a59f De-dup FILE output for each license (flutter/engine#10945) (#38996)

git@github.com:flutter/engine.git/compare/29469f39c13a...ab097a59faf5

git log 29469f39c13a..ab097a59faf5 --no-merges --oneline
2019-08-21 stuartmorgan@google.com De-dup FILE output for each license (flutter/engine#10945)

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