Neon version of rftbsub_128()
Neon version of rftbsub_128()

The performance gain on a Nexus 7 reported by audioproc is ~4.5%

The output is bit exact.

BUG=3131
TESTED=trybots and manually
R=bjornv@webrtc.org, cd@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/19919005

Patch from Scott LaVarnway <slavarnw@gmail.com>.

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: ac800c8004c718a87aa46e0795f3f654e29245f9

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc