This CL adds an nonwindowed spectrum of the linear filter error to use in the NLP computation. Bug: webrtc:8661 Change-Id: I45bc9bb3eb8eeac0c5d6adb414638eb12b635a27 Reviewed-on: https://webrtc-review.googlesource.com/38701 Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org> Commit-Queue: Per Åhgren <peah@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21583}