Allow a custom version of audioproc_f in APM-QA.
Bug: webrtc:7494
Change-Id: Id9adffd63927202d868bc2fc8b6a54c8e6b07039
Reviewed-on: https://webrtc-review.googlesource.com/4060
Reviewed-by: Alex Loiko <aleloi@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20033}