avcodec/ac3enc: Use avpriv_float_dsp_alloc()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/aacenc: Use avpriv_float_dsp_alloc()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/on2avc: Use avpriv_float_dsp_alloc()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>