[libc] Prevent overflow from intermediate results when adding UInt<N> values.

Prevent overflow from intermediate results when adding UInt<N> values.

Reviewed By: orex

Differential Revision: https://reviews.llvm.org/D131095

GitOrigin-RevId: d1a9ba7b67038a8d2560fa4b5abac59ddda28f11
3 files changed