When sbr->reset is set in encode_frame, a bunch of qsort calls might get made.
Thus, there is the potential of calling qsort whenever the spectral
contents change.

AV_QSORT is substantially faster due to the inlining of the comparison callback.
Thus, the increase in performance should be worth the increase in binary size.

Tested with FATE.
Reviewed-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>