This change just wraps the openssl key derivation functions in a simple
interface in a similar way to how we do it for messagedigest.h so we aren't
coupled to openssl in the core implementation.
Bug: webrtc:9917
Change-Id: I8556bd6e38b7da34d93abbe29415c3366f6532ba
Reviewed-on: https://webrtc-review.googlesource.com/c/107981
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Commit-Queue: Benjamin Wright <benwright@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25440}
