From my description,
> For gcc, lame has a big "experimental optimizer" section with
> -march=native and other flags that we don't want in bulk builds
> (but might be useful for self builds sometimes). It's controlled by
> --enable-expopt (the default is "none" to disable it),
>
> There is a similar section for clang which is just outside the "expopt"
> block. I think that's a mistake, but I don't want to poke around too much
> as they have other mistakes in their configure script nearby and I don't
> want to go down that rabbit hole ;)
>
> Here's a simple diff to neuter the check.
a1af0ec998