Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
This commit defines a schema and YAML serialization for a significant
portion of our AST. The API ingestion is a work in progress.
See design discussion in ModuleAPIDiff.cpp.
Swift SVN r23938