Summary:
This changes the `YOGA_ROOT` to `YOGA_ROOTS` in `YOGA_DEFS`. This allows the
inclusion of Yoga in the exported Components libraries directory and
back-references to the nested dependencies within it.
Reviewed By: rspencer01
Differential Revision: D4721745
fbshipit-source-id: 2dc9d4a730076510aed02027cb6713f6326c588d
9b13fdeae4