Splits 'modules/audio_processing:audio_processing' target. The files in modules/audio_processing/agc now are in targets in that folder. Reason for doing this was to include modules/audio_processing/agc/agc.h from another target in the dependent CL https://webrtc-review.googlesource.com/c/src/+/86603 This could help reducing the binary size in the future. Bug: webrtc:7494 Change-Id: I61f50ab6d5ce24d19f4097e0f3fa8b0170010887 Reviewed-on: https://webrtc-review.googlesource.com/87422 Commit-Queue: Alex Loiko <aleloi@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23873}