Add option to disable native lib reachability, tune down native method reachability
Add option to disable native lib reachability, tune down native method reachability

Summary:
Two things:

- Add ability to disable reahability by name from native libs. It may be too conservative and for now may be better to by hand mark things as "need to keep"
- Dont mark every method in a class as reachable by name if theres a single native method defined on the class (only mark the class and that specific method as reachable by name)

Reviewed By: int3

Differential Revision: D14256923

fbshipit-source-id: 202e8903d861aed059d3fb364fdba0da86d70a12

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