[native] replace uint with unsigned int

Summary:
Emscripten compiler (for some reason) does not recognize uint, and cause: error: use of undeclared identifier 'uint'; did you mean 'int'?

Depends on D8488

Test Plan: N/A

Reviewers: michal, tomek, jon, atul

Reviewed By: michal

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D8489