Fix audio record pre-processing proc_buf_out consistently initialized. intermediate scratch buffers consistently initialized. prevent read failure from overwriting memory. Test: POC, CTS, camera record Bug: 62873231 Change-Id: Ie26e12a419a5819c1c5c3a0bcf1876d6d7aca686 (cherry picked from commit 6d7b330c27efba944817e647955da48e54fd74eb)