Canonicalize supported CPU feature set

Canonicalize supported CPU feature set

Forwarded: not-needed

Explicitly set supported CPU features.

  - Disable Intel SSE and SSE2 on i386, since Debian supports some i386
    processors without those extensions. Keep them enabled on amd64, since all
    amd64 processors have them.

  - Disable Intel SSSE3 entirely, since no i386 processor supports it and Debian
    supports amd64 processors without it.

  - Disable NEON on armel and armhf, since no armel processor supports NEON and
    Debian supports some armhf processors without it. Keep it enabled on arm64,
    since all arm64 processors have it.

Gbp-Pq: Name cpu-features.diff