Use the C++-style stdlib headers, add `std::` prefix, in order to avoid implicit casts to double. Bug: None Change-Id: I78d9caaee715be341d2480c6d5e769068966d577 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/133625 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Commit-Queue: Oleh Prypin <oprypin@webrtc.org> Cr-Commit-Position: refs/heads/master@{#27905}