Add a safe static_cast where we compare ints of different signedness (#496)
Add a safe static_cast where we compare ints of different signedness (#496)

Closes #496

COPYBARA_INTEGRATE_REVIEW=https://github.com/google-research/raksha/pull/496 from google-research:static_cast@bgogul d4bfa015d20d3558806cade0bbcf1bb5ce675c94
PiperOrigin-RevId: 438192720

google-research/raksha,google-research/raksha,google-research/raksha,google-research/raksha