2.2.2: Moving beyond libffi

Posting as a PR for review.

Unit testing verified:
 - [x] Mac x86_64 (10.9)
 - [x] `x86_64` iOS simulator (7.1)
 - [x] `i386` iOS simulator (7.1)
 - [x] `arm64` (7.1)
 - [x] `armv7`/`armv7s` (7.1)

Manual testing verified:
 - [x] Mac x86_64 (10.8)
 - [x] `i386` iOS simulator (6.1)
 - [x] `armv7`/`armv7s` (6.1)