LowCutFilter::BiqueadFilter::Process: Fix UBSan fuzzer bug
LowCutFilter::BiqueadFilter::Process: Fix UBSan fuzzer bug

(left shift of negative value)


Bug: chromium:735593
Change-Id: I9f1165370d850456480fbb22ce2434bf933a420b
Reviewed-on: https://chromium-review.googlesource.com/552136
Commit-Queue: Alex Loiko <999d0b481e5703ad7006f0848e249f8b2c3f29bd@google.com>
Reviewed-by: Per Åhgren <3616c2c8a2c30a769c5419f89b4a810ea6e2f079@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#18812}
TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc