[opus] configure options for x86

[Jonathan Lennox]

> On Nov 16, 2015, at 6:27 PM, Sean Darcy <seandarcy2 at gmail.com> wrote:
> 
> Thanks for the prompt and helpful replies.
> 
> Built with --enable-custom-modes --disable-static --enable-intrinsics --enable-rtcd --enable-float-approx
> 
> All worked. Only thing odd, rtcd was not enabled:
> 
>       Floating point support: ........ yes
>       Fast float approximations: ..... yes
>       Fixed point debugging: ......... no
>       Inline Assembly Optimizations: . No inline ASM for your platform, please send patches
>       External Assembly Optimizations: 
>       Intrinsics Optimizations.......: x86 SSE SSE2 SSE4.1 AVX
>       Run-time CPU detection: ........ no
>       Custom modes: .................. yes
>       …………………..

Is your compiler configured to generate AVX code by default? If the configure script detects that it can use the various CPU variants unconditionally, it won’t bother to use RTCD.