Update fontchain_lint to test new emoji font

The new emoji font has been update to Unicode 10/Emoji 5, and has a
new mechanism for flag fallbacks. It also shares glyphs between
gendered emoji and non-genders ones.

Test: make fontchain_lint passes
Bug: 34688862
Bug: 33276970
Bug: 34738377
Change-Id: I4d43b8c777deb93be1e6a784eaa109e2e7febd7d