Annotate third_party imports

See also http://cl/572542822 and http://cl/572540001

Some of these are not used in G3, but showed up in my
search anyway, so might as well avoid future potential errors.

Change-Id: I43711ee4c574e36a18f906f5f6d8aa72bde4a5db
Bug: b/237076898
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/765256
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
42 files changed