Add GIT_SYNC_DEPS_SHALLOW_CLONE to git-sync-deps

Allows users to avoid cloning the entire history.

Change-Id: Ifaed74f3851d9a3e21d9e4ee23cc7b641c044f8b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/780137
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
1 file changed