isom: Don't use 'stz2' for tracks containing some CODECs in 3GPP.
isom: Don't use 'stz2' for tracks containing some CODECs in 3GPP.

canbal/l-smash,maki-rxrz/L-SMASH,l-smash/l-smash,maki-rxrz/L-SMASH,silverfilain/L-SMASH,silverfilain/L-SMASH,l-smash/l-smash,canbal/l-smash,silverfilain/L-SMASH,l-smash/l-smash