[opus] silk_warped_autocorrelation_FIX() NEON optimization

[Linfeng Zhang]

Hi all,

I'm sending patch "Optimize silk_warped_autocorrelation_FIX() for ARM NEON" in an separate email.
It is based on Tim’s aarch64v8 branch https://git.xiph.org/?p=users/tterribe/opus.git;a=shortlog;h=refs/heads/aarch64v8

Thanks for your comments.
Linfeng