Set the 32 Band Audio Equalizer settings.
\param mh handle
\param channel Can be MPG123_LEFT, MPG123_RIGHT or MPG123_LEFT|MPG123_RIGHT for both.
\param band The equaliser band to change (from 0 to 31)
\param val The (linear) adjustment factor.
\return MPG123_OK on success
Set the 32 Band Audio Equalizer settings. \param mh handle \param channel Can be MPG123_LEFT, MPG123_RIGHT or MPG123_LEFT|MPG123_RIGHT for both. \param band The equaliser band to change (from 0 to 31) \param val The (linear) adjustment factor. \return MPG123_OK on success