Update to Speex

[Jean-Marc Valin]

> Iaxclient uses some elements of struct SpeexPreprocessState to bring
> Speex AGC gain out to the mixer. Struct SpeexPreprocessState is made an
> opaque type in speex 1.2beta2 and later, which means iaxclient fails to
> build.

Yes, those should never have been exposed directly because the
definition of the struct depends on compile options (mainly float vs
fixed point).

> Are there any plans to expose speech_prob and loudness2, members of
> struct SpeexPreprocessState, in an API which can be used by iaxclient or
> what are you recommendations?

This is something I'm willing to do. Can you (or someone else) send me a
patch that exposes these parameters through the _ctl() interface?

	Jean-Marc