Summary:
Add *.pyi type stub files for most of the native C extensions.
This allows Pyre to type check functions that use these extensions.
These type annotations likely aren't complete, but contain enough information
to allow Pyre to pass cleanly on the existing type-checked locations in the
code using these modules.
Reviewed By: xavierd
Differential Revision: D19958220
fbshipit-source-id: 85dc39a16e595595a174a8e59e419c418d3531be